Startled into action, Jim Landor straightened in his seat. He peered eagerly through the forward visiplate of the tiny rocket-plane.

From the Martian metropolis that nestled in the opposite hemisphere, thirteen hundred miles away, he had taken the poorly-mapped, wearisome, rocket-course of the Polar route in order to save time. Thus he avoided being hampered by the magnetic storms raging over the Red Desert at this season. At least, so he'd told his friends.

But the real, the all-important reason he had kept to himself. It was not only that they would have laughed at him, that mattered little; but that a growing, nameless dread made him even more reserved than usual. He smiled thinly now as he visualized their reactions had he dared mention the mythical city of M'Tonak. M'Tonak, city of forgotten men, where reposed the fabulous emerald large enough to ransom a world!

Yes, Jim thought without bitterness; at last he had joined the fatal number of men, usually Earthmen, who had searched for M'Tonak. He was persuaded against all reason that it did exist somewhere among the polar wastes, and it was most imperative that he find it! He was sure that then he would find his brother too, who had disappeared scarcely a month before. In his perilous passage above the Cap, Jim had zig-zagged the rocket-plane dangerously off its course, searching the limitless white wastes with the intentness of desperation. But in vain.

"Well," he murmured now, "no M'Tonak, so I'll settle for Riida—for the time being."

The tiny Martian town was beneath him, its crazy conical structures reaching up like pointing forefingers. Jim's hand came down on the descent lever. A ghostly whirr disturbed the stillness as the plane's stubby wings sliced the atmosphere on its downward glide. It contacted gently, plowing a shallow furrow in the powdery sand that rose cloud-fine to engulf him as he climbed out. Already he saw two men hurrying toward him from the town.

"One of them must be Conley," he decided and went forward to meet the mine superintendent.

"Hello, Jim Landor, welcome to Riida!" Conley shook hands with a quiet, unobtrusive pleasure that seemed sincere. Jim liked him immediately. He noted his straight-forward eyes, the faint burr of his booming Irish voice and the little mannerism of thoughtfully rubbing his hand across his massive chin.

The other Earthman, Conley introduced as Wessel, the newly arrived surveying engineer for "Tri-Planetary Mining." As Jim glanced at the thin features and small wiry frame, he sensed something hard behind the man's clouded eyes. Wessel remained silent, smiling inscrutably as he listened to their conversation.

"So you came across the Cap, eh Landor?" Conley said friendily, taking Jim's arm as they trudged toward the town. "Any sign of M'Tonak?" And as Jim looked at him sharply he hastened to add: "Not that I'm poking fun at you, lad. But you're news now, you know, same as anyone who goes seeking for M'Tonak. Heard a news-story about you on the Trans-telector not more'n a couple hours ago."

"I thought my flight was a secret."

"Ah, no! No man's flight is secret who comes over the Martian Cap. That can mean but one thing. Yep, the legend of M'Tonak is rife once more, first time in two years. You're supposed to be searching for the lost city ... now, what would ye be wanting with an emerald that big?" Conley half joked, lapsing into his Irish brogue. "Faith an' it makes a man's head swim to think of such riches."

Jim Landor did not smile. He looked at Conley seriously. "I've only been on Mars a year, but naturally I'd heard stories of M'Tonak long before that. You called it a legend just now. Tell me, what is your honest opinion?"

"Well, lad. Certainly there's something up there to cause these stories to persist." Conley rubbed his chin thoughtfully. "Maybe it's an ancient city called M'Tonak and maybe it ain't. But men in search for it have disappeared too regularly, hardly men who wouldn't ordinarily fail to return from the Polar wastes. And—and if there is a M'Tonak, your brother may have reached it."

"I shall find my brother," Jim said with a soft certainty. "That's why I'm here. What about that Martian, the one you said accompanied Frank into the Cap? Is he here now?"

"He is, and you shall talk to him. But, lad, I'm afraid he can't tell you any more than I did in the letter."

"I want to hear it first hand."

"Sure," Conley nodded understandingly.

They walked in silence through the powdery sand, nearing the town. Jim glanced at Wessel, silent still, his hieratic smile barely perceptible. There was an uncanny aura to the man as if he were immersed in a world of his own where Jim and Conley had no part.

"There's Frank's mine," Conley pointed beyond the town toward a low line of hills. "If you look close you can see his shack over there. As you probably know, he was—well, the independent type. Refused to sell out to Tri-Planetary Mining. That's why he went on north when his claim petered out, in an effort to find the source of the radite veins. Want to go over there and look around?"

"Later," Jim said shortly.

They entered the sprawling town with its curious Martian dwellings. Jim had never ceased to marvel at them. They were conical and glistening, built of a reddish manufactured silica. They were surrounded by an ascending spiral dotted with entrances to the very top. Jim sometimes wondered, too, at the manner in which Martians tolerated so much from the Earthmen. But then, it was well known that activity to a Martian was the final degradation. They looked upon the exertions of the Earthman in a mixture of uncomprehending wonder and supercilious amusement, much as a human might watch the eternal hustle of a colony of ants. Theirs was a world of philosophic contemplation, peace and indolence.

Now, as they proceeded along the straggling main street of Riida, Jim wondered about them even more. From various ramps of the conical buildings residents watched them silently. Tall, wasp-waisted Martians, dark and leathery, passed them leisurely on the street without a word. They weren't sullen, it was as though they didn't care. Jim peered into their heavy-lidden eyes. Colorless eyes, always. He was startled at the somnolence he saw there. It struck a vague disturbing note in his brain that was dashed away by Conley's booming voice:

"Here we are!"

They had reached a squat, basaltic building which bore the legend TRI-PLANETARY MINING CORPORATION.

"Enter the lair of the Octopus," Conley laughed, glancing at the gilded sign above him.

Wessel frowned at the words, and by that token Jim knew that he was a Corporation man to the hilt.

Within, Jim found himself in an atmosphere as far removed from Mars as day is from night. The office was plain and unpretentious. There was an old-fashioned desk, a few chairs and some iron lockers against the wall. On the walls, in curious contrast, were pictures of cinema stars several years out of date, and a few yellowed maps of the company's workings.

"Not only has Frank's claim petered out," Conley explained, "but Tri-Planet is beginning to. That's the reason Wessel's here, to try and trace these radite veins to their source. We think they must stem from somewhere up in the Cap."

Jim nodded. "You haven't many Earthmen here now, have you?"

"About a dozen," Conley shrugged. "More than enough to handle what little radite's left."

"And we wouldn't even need them," Wessel spoke for the first time, "if we could get these damn lazy Martians to stir themselves."

Jim turned his gaze on the man with slowly dawning wonderment, and would have spoken, but was interrupted by Conley:

"Jim, we thought we'd head up into the Cap in the morning, four or five of us. Wessel wanted to leave several days ago, but I insisted on waiting for you. However, I can't say how far north we'll be going. It all depends on the radite traces."

"Thanks, Conley, I really appreciate it. All I know about this Polar Cap is what I saw flying over it. What do we do, make the trek afoot?"

"Afoot, he says!" Wessel scoffed before Conley could answer. "Man, what a lot you've got to learn yet about that country up there!"

"No," Conley answered, with a distasteful glance at Wessel. "Most men who've tried it afoot have not come back. We're trying it with a couple of sleds. Motor-driven, of course, of very little metal alloy. Furnished benignantly by Tri-Planet Mining, since it's to their advantage that we find new radite deposits." The slight scorn in his voice was not lost on Wessel. "We figure it'll be a two or three day trip each way."

"But of course," Wessel said suavely, "if we find M'Tonak or any other cities up there with big fabulous emeralds, we'll forget about the radite."

Jim was fast learning to dislike this man; he turned to Conley. "I think I'll see this Martian you were telling me about, the one who accompanied my brother."

"Kaarji? Sure. I'll go fetch him."

"Better take me to him instead, I'd rather talk to him alone."

As Conley had said, Kaarji wasn't of much help. The tall, leathery, heavy-chested Martian was even more taciturn than the usual members of his race. He seemed to show a distrust of Jim.

However, he did agree to accompany Jim across the mile strip of desert to Frank Landor's mine nestled against the hills. As they trudged through the sand in silence, Jim glanced occasionally at Kaarji. He was sure he had made it plain that he was Frank Landor's brother. The Martian wasn't dumb, he knew why Jim was here.

With a friendly and almost instinctive gesture Jim offered the Martian a cigarette. Kaarji accepted it, looked at it with distaste as though he had tried them before and abhorred them; but he placed it clumsily in his lips nevertheless and smoked it valiantly. At the same time he reached into his pocket and handed Jim a few tiny purplish objects. Jim accepted them, looked at them and shuddered. He had heard of Martian tsith stems and knew that they made almost all Earthmen violently ill. Nevertheless he plopped them into his mouth and began chewing.

Kaarji looked at him approvingly and gave a grotesque smile. As though the Earthman's act were a signal, he began talking.

"I don't like it in town," Kaarji said. "Too many Earthmen. I like it over here."

"At Frank's mine, you mean?"

"Yes. Frank Landor was a fine man. I am sorry he did not come back."

"Perhaps he will come back," Jim suggested.

But Kaarji shook his head.

It took very little effort then to get the entire story. It seemed that Frank Landor and Kaarji had trekked four days into the Martian Cap. Only Kaarji had ever gone that far before. Late on the fourth day, as they camped, Kaarji was awakened by a shout from Frank. He had leaped up and glimpsed Frank Landor running toward a vehicle that rested at the bottom of an icy decline....

Here Kaarji faltered slightly in his story. He had not seen the vehicle plainly enough nor long enough to describe it as other than a car, seemingly unlike any he had ever seen before. It was simply round and grayish and metallic, and completely enclosed. It had a bluish beam of light in the front of it. Frank Landor had seemed to enter the car—and then it sped away with him.

"Kaarji, try to remember," Jim said to the Martian now. "Frank entered the car of his own volition? You saw no one else, no other person?"

"No one else." Kaarji seemed sure of it.

Jim shook his head in puzzlement. This was the same story Kaarji had told Conley, there were no discrepancies.

They walked on to the mine in silence. Jim examined several tunnels leading back into the hills and saw that Frank's claim had indeed petered out. In his iron-walled cabin, everything was left as though Frank had merely gone and intended to return in a few days.

"Let's go back," Jim said finally. "Nothing we can do here."

On the walk back to Riida, Jim thought that Kaarji looked at him several times as though he were going to speak. But when Jim questioned him, the Martian shook his head negatively. He offered Kaarji another cigarette but this time it was declined.

It was not until then that Jim realized he was still chewing on the Martian tsith stems, and that Kaarji was grinning at him.

It was not until he reached the edge of town that he became violently ill.

II

The sun rose on a crystal clear morning and glanced beckoningly from the white expanse that capped the cliffs a few miles distant. Five men were making the trip: Jim and Kaarji, Conley, Wessel and Lewis, the latter, one of the workmen who had had some Polar experience.

The motor-sled parts were light but bulky, and it took a dozen men to transport them across to the cliffs and up into the Cap, where they would be assembled.

"I want to tell you something about Kaarji," Conley said, walking beside Jim as the trek began. "He's not like other Martians, not philosophic and indolent. On the contrary he seems—well, restless."

"I know the type," Jim nodded. "I've seen a few of them myself, even in the Capitol City; amazingly energetic for Martians, restless and perpetually wandering as though seeking for—for something vague and unknown even to them."

"That describes Kaarji, all right," Conley nodded emphatically. "Jim, three times in the past year he's left here abruptly and trekked alone up into those Polar wastes. He'd be gone for days and then show up here again, exhausted and brooding, as if he'd just missed his goal. And the last time was with Frank Landor. That mean anything to you?"

Jim shook his head puzzledly.

"Now I wonder," Conley murmured, "what he always finds so interesting up there in that wilderness?"

"Probably doesn't find anything. Maybe he's only—seeking. Perpetually seeking."

"Seeking M'Tonak?"

"Maybe."

Conley scoffed. "Now what would Kaarji do with the emerald of M'Tonak if he did find it? Of what value would it be to any Martian, to the whole dying Martian race?"

"Maybe it isn't the emerald the Martians are interested in."

Conley was startled, glanced sharply at him, but Jim kept his eyes on the huge bulk of Kaarji ahead.

They reached the black cliffs and entered a narrow defile that led gradually upward, tortuously. The rock was a soft, igneous basalt which at times made footing extremely hazardous. After an hour of this Kaarji stopped abruptly in a level place.

They leaned thankfully against the cliff wall, and stared out upon the curving gleam of the Red Desert far below. There the hazes of pinkish dust were beginning to drift and the sun was beginning to bite.

They continued when Kaarji continued. An hour later the air had become a chilling blast sweeping down the widening ravine. Luckily the ascent was becoming less steep as they neared the top. It levelled off into a shallow little gorge, then they were beyond that, emerging out onto the plateau.

Scattered patches of dark rocky terrain showed here, where green growing things struggled pitifully to maintain a meagre existence. Less than a mile away the real Cap began, dazzling white and forbidding.

Reaching there, the two sleds were assembled in a few minutes. The five who were to make the trip now readjusted their packs and put on the priceless coats of Praaka fur, unbelievably light and cold repelling. They also painstakingly tightened the high fabricord leggings Conley had insisted they wear. Jim wondered why, but asked no questions as he followed suit.

The supplies were on the sleds, but each man carried a fully charged electro-pistol and a small, light metal tank strapped to his side.

"Acid spray," Conley explained laconically. "Don't worry, you'll realize the use for it before long."

Now the real trip began.

"Kaarji, you and Lewis take the first sled," Conley instructed. "We'll follow."

The Martian nodded. The motors purred and the sleds moved slowly away.

"Yes, we'll follow him," Wessel murmured. "Just as long as he sticks fairly close to the radite veins, we will. This is what I'm going by." And he touched the little metallic device at his wrist, which Jim knew was susceptible through super-sensitive coils to all radite emanations within a radius of several miles.

Conley frowned but nodded mute agreement. And now for the first time it really dawned on Jim that he and Kaarji were apart from these other men. He and the Martian were up here seeking, not radite deposits, but something else. The same thing but for different reasons. Jim determined to try, at the first opportunity, to probe into that big Martian's mind.

Now they were speeding into the real Polar vastness. Kaarji's sled ahead of them dipped and rose across long icy undulations. The terrain was wide and white and peaceful as far as Jim could see. He began to wonder why men had never been able to penetrate very far up here. Even afoot it ought not to be hard, but this was ridiculously easy! As he huddled there in his place on the sled he was very warm and cozy beneath his coat of Praaka fur. He began to get drowsy....

Jim awoke with a start from the deep, firm depths of somnolence. He was aware that they had been moving for a long time, probably many hours. Now the sky was dark above him and he could see a few stars. But something had shattered his drowsiness to jerk him back to reality, and he wondered what it was.

Then he knew, as it came again. There was a sudden movement beneath them. The sled lurched crazily. Conley was shouting something, as their sled pulled up beside Kaarji's, which was lying half on its side.

The men stepped down. Again there came that sudden movement, and Jim nearly fell! Startled, he looked down and saw that the very ice cap was moving beneath their feet, or rather it was expanding! Long lines began to appear in every direction. As far as he could see, the surface was a vast mosaic pattern.

Conley stood there with his hands on his hips, staring around. Wessel was cursing softly and looked angry.

"This wouldn't have happened," Wessel said, "if you'd taken my advice and left two days ago! Tomorrow it'll be worse. It'll slow us to a walk. We may as well not have brought along any sleds."

"It would've happened anyway!" Conley snapped testily. "It's just our damnable luck that it had to come early this year. I didn't expect this to start for another month yet. Well, we may as well camp here and get a good start in the morning."

Jim looked at the mosaic pattern across the ice and was relieved to see that it had stopped moving. He peered down into a crack an inch wide, where a billowing powdery stuff exuded to spread thinly over the surface. He touched the stuff with his bare hand. It was uncannily different from snow, being infinitely more powdery yet dazzling white and deadly cold.

"You're witnessing the start of the Polar Cap's receding," Conley explained with a wry smile. "It does that twice a year, you know, getting smaller to about half its present size.

"Receding!" Jim exclaimed. "The damn stuff's expanding, you mean."

"It only looks that way. This is just the preliminary. Soon the extreme edges will vanish away and then the entire Cap will begin receding, for some strange reason. When that starts to happen, too bad for any man caught up here. Frankly, Jim, I should say that, if this continues tomorrow, we ought to head back."

That struck an ominous note in Jim's heart, but he said nothing. To return now would mean they must wait several months before making another attempt.

It was while helping to unroll the wide fabricoid mats that Jim felt the sharp, biting pain just above his knee. He ignored it at first. Then it came again, and he looked down. He saw a pale blue, tubular thing about four inches long. It had bitten through his clothing and into his flesh above the knee. Quiescent now, it clung there, and its transparent bluish tint was taking on a crimson flush as it fed upon his blood.

With a loathing horror Jim reached down and pulled the thing from him. It did not come away easily. He flung it to the ice and tried to crush it with his heel. It seemed amazingly rubbery, resilient, as it darted away from under his foot. Then he saw that others had attached to his fabricoid leggings, and were inching their way upward.

Desperately he tried to brush them off, but they clung tenaciously. Another one bit through his trouser leg and into the flesh. It was cold and loathesome to the touch, but he tore it away with his fingers. Then he staggered back, as he saw that the ice was swarming with the things.

"Your acid tube, man, use it!" he heard Conley cry. "That's all that'll stop 'em!"

Already the men were up-ending the sleds, using them as a barricade from behind which they swept the ice with a thin misty spray. Not wishing to chance that acid on his own person, Jim tore the things from his legs one at a time and flung them out into the spray. They writhed and shrivelled and curled upon themselves, lifeless and blackened.

Others were coming up from the crevices now. The ice was a thick, bluish writhing mass of them. Jim added his spray to the others, sweeping it low across the ice. The acid misted and clung there close to the surface, until gradually the greater mass of the bluish things retreated back into the depths.

Kaarji opened a pouch he carried always with him, took out some tsith stems and placed them in his mouth. He arose and stood gazing out to the north. Jim watched him.

"Whew!" Conley gasped, wiping beads of cold perspiration from his brow. "Just in time! Let those things once get a foothold up here and there's no stopping them. I guess we've settled for most of them, though, they won't come again."

"But what the devil are they?" Jim asked. "And how can they subsist in this barren country?"

"It's not so barren. Far below the ice are green growing things, at least this far south there is. Those blue tube-things ride down with the ice twice a year, feed, and then migrate back to the north.

"Vegetarians, eh?" Jim grunted. "Then what were those two chewing on me for?"

"Blood's something comparatively new to them, and it seems to drive them wild. They can sense it for amazing distances. They come flocking beneath the ice to wherever anyone stops. There's a story of an Earthman who was lost up here once, and—Well, never mind. Anyway we'll take turns on guard tonight."

Jim slept fitfully. There were fragmentary nightmares of the ice opening to spew hordes of bluish tube creatures up at him. He was glad when Kaarji awakened him for his turn at guard.

But Kaarji did not return to sleep either. He seemed restless and brooding. He sat beside Jim against one of the sleds, and for a long time there was silence as he stared far out to the north with troubled eyes.

"Jim Landor," he broke the silence at last, "there is one thing I did not tell you."

"I thought there was."

"Frank Landor and I found something. The body of a man in the ice far to the north of here. It had been there a long time."

Jim merely waited for him to go on.

"In his clothing we found some of these." Kaarji fumbled in his pocket, and handed something to Jim.

It was a piece of metal, flat, round and amazingly light. It seemed to have once been part of some ornamentation. What interested Jim, however, was not what it might have been, but rather the metal itself. It was a dull greenish-gray in color and strangely different to the touch from any metal he had ever known. It was somehow reminiscent of radite, but only faintly. In it was a subtle suggestion of—yes, of fabulous strength and power!

In the dim grayness of that Polar night Jim looked at Kaarji and said in a voice he did not recognize as his own:

"Kaarji, do you realize what this means? Up here somewhere there is a city, a former civilization—a M'Tonak! That man you found dead—he reached M'Tonak and was coming back with the news when disaster overtook him! But that might have been many years ago....

"Tell me something, Kaarji. Why have you come up here three times before? Are you seeking M'Tonak?"

"I do not know. Something calls me. Something inside. And I only know that I must go."

"Is that all, just something calling you?"

"That is all. Except that this time it is different. This time I know that I shall reach—whatever is calling me, and I shall not return. I am sure of it."

Jim sat there for a long time, pondering, watching Kaarji pace restlessly back and forth. The Martian was in a strange mood this night. A foreboding mood. Jim gave up puzzling about it, and examined again that strange piece of metal. Here at last was proof of M'Tonak, perhaps the first proof any man outside had ever had! He felt an exuberant hope rising in him.

"Anyway, Kaarji, thanks for telling me about this. Mind if I keep it a while?"

"I want you to have it, Jim Landor."

III

They were away early the next morning, speeding ahead of a graying dawn. Wessel was wrong, the ice no longer shifted beneath them; but the biting sun had not yet risen. Now Jim noticed that Wessel constantly consulted the device at his waist, which registered the proximity of any radite. Apparently, however, he was satisfied with the route Kaarji was taking.

It was about noon when the terrain began to surge gently again as though with a life of its own, and the mosaic pattern of cracks re-appeared. But this was not enough, as yet, to stop them. What did stop them was Wessel, who called a halt a few hours later.

"Must be some Floaters near here," he told Conley. "I can tell by the way this thing's acting." He tapped the radite-finder, whose needle was gyrating erratically.

"Floaters?" Jim asked. "What are they?"

"Trouble," Conley groaned. "More denizens for you to get acquainted with. You'll see before long."

"There they come now," Wessel pointed. "We may as well wait here, and get rid of them once and for all."

A long line of tiny dots had appeared low on the horizon. They came rapidly nearer and proved to be perfect spheres about a foot in diameter, apparently with an uncanny power of levitation! There were several dozens of them. Hovering in the air, they circled around the men. A few of them darted in close, experimentally.

Jim threw up a hand instinctively as one zoomed too near his head. His fist contacted the taut, metallic skin of the thing. He felt a slight but inconsequential electric shock. The Floater bounced back lightly as a feather. It hovered there, took on a shimmering, greenish iridescence as though it were glaring at the Earthman. Jim felt an uncanny chill across his brain. He was sure these things were intelligent! Again it zoomed in, but again Jim shoved it back easily.

"That's it," Conley said in general to the men who were staving off the pesky things. "Make them keep their distance. They're really not dangerous, if we keep them away from the metal sleds. That's what they want."

The Floaters at last seemed to call a council of war. They gathered in a group behind the men. Conley took advantage of this, and gave the order to move again. But the Floaters followed slowly, longingly. A few of them made tentative darting attempts, but the men were too wary. Suddenly then, en masse, the Floaters launched their real attack.

They came from all sides and the men were overwhelmed. A few of the spheres alighted on a sled. The metal began to crumble. Cursing, Conley knocked them away; but others alighted.

"Protect the sleds!" Conley yelled.

The men were trying to. A sphere attached itself to the metal fastenings of a pack, and clung there voraciously. The metal crumbled, disappeared, and the pack spewed its contents over the ice. Instantly the Floater darted to the contents, seeking more metal. Lewis drew his electro-pistol, but immediately a Floater attached itself to it; the weapon dissolved, disappeared, as the creature took on a rosy radiance of heat-energy.

"Holy Hannah!" Lewis gasped.

Conley was cursing volubly now, but he was suddenly cool.

"All right, you men, let 'em have it—all at once! Blast 'em out of the air."

They threw themselves flat on the ice and swept their weapons around in a solid, crackling barrage. That was the beginning of the end for the Floaters. They exploded in corruscating riots of bluish sparks wherever the electro-beams touched. Soon the ice was littered with their lifeless, deflated husks. The remaining ones sped far away out of danger, and they did not return.

"I hated to do that," Conley sighed, "'cause I kind of like those creatures. They have intelligence of a sort. They're harmless enough ordinarily, except for their voracious appetites for metal!"

"The damn things sometimes visit our mines to the south," Wessel said, "but I'm kind of surprised to find 'em away up here. That can only mean one thing, though. We're on the right track! The radite must stem from one huge central deposit somewhere up here!" His eyes gleamed at the thought.

To Jim it meant even more. The converging radite veins, Kaarji's story of the perpetual lure that tormented him, and most of all that mysterious bit of strange metal—all this pointed to one thing, a secret somewhere to the north. And that secret was M'Tonak. Jim was sure of it now. He was sure they would reach it, that they were meant to reach it.

The thought surged within him, made him restless and foreboding. So that when, late that day, the car came—the silent mysterious vehicle from out of the north, just as Kaarji had described—Jim was not surprised.

He had been almost expecting it.

It was while they were making camp. They were rolling out the fabricoid mats and setting up the little atomo-stoves. Jim missed Kaarji, looked around and saw the Martian at the crest of the long, smooth rise at the foot of which they had stopped.

Jim drew his coat of Praaka fur closer around him and walked out to where Kaarji stood. Not until he had gained the crest of the slight ascent did he see that the Martian was in his strange mood again, standing quite still, staring out to the north.

Jim approached very silently. He stood unmoving by Kaarji's side. Now he almost felt it too, an eerie feeling as though ghostly, insistent fingers were tugging at his brain. Almost, a fascinating wisp of a voice created an urgency within him. But that was imagination! He knew it, even as he drew back.

For a full minute they stood there in silence. Then Kaarji, without even glancing at him, spoke in his curiously clipped monnotone:

"So you feel it too, Jim Landor."

"I—I thought I felt something."

"The same thing that I have felt. But I have felt it stronger."

Stretching out below was a long gentle decline, and beyond were the familiar vastnesses of the Polar wastes. Now Jim found himself scanning the far horizon. He felt on the very verge of something strange—and momentous.

Kaarji leaned tensely, suddenly forward. Not the slightest show of emotion was in his voice as he stated:

"It is coming. I know it. It will be here very soon."

Jim did not ask what was coming. He knew. He had known all the time. He stared outward, following Kaarji's gaze, but could see nothing. He waited impatiently as the Martian never once removed his eyes from the horizon. Minutes passed.

Then ... much nearer and so clear that even Jim could not mistake it, a dot of light flashed across their vision. Immediately it was gone, hugging the terrain closely as though it had dipped behind an ice dune. It appeared again in the near distance, moving swiftly, unerringly toward them. It resolved itself into a penetrant beam of bluish light, the forward light on a speeding ghostly vehicle.

Abruptly it slowed. It crept silently to the very foot of the slight slope below them. Breathless with wonderment, Jim waited for something to happen. Nothing happened except that the bluish light blinked abruptly off. No door opened. No one nor nothing emerged. Even at this close distance the conveyance was discernible only as a grayish, ghostly shape.

Then Kaarji was running down toward it. Jim was suddenly torn between two desires. He stared after Kaarji and then back at the camp. He shouted to Conley and the others, and saw them look up and start toward him; then he was dashing madly after Kaarji who had almost reached the ghostly conveyance now.

When Jim reached there, Kaarji was staring at a dark, narrow entrance in the metal hull. "It was already open," the Martian murmured. Then, as though it were expected of him, he stepped unhesitatingly inside.

Jim waited for a single instant during which he surveyed the hull of the vessel. It was not any type of sled, as he had thought; indeed it did not touch the surface at all, but hovered a full foot above the ground. He heard a gentle humming as though of ionization beams. He followed Kaarji inside.

There were no sort of controls that he could see; only a long row of seats filled the entire space. Kaarji had found a button that turned on some overhead lights. Still nothing happened.

By this time the other men had reached there. Conley was stammering, "Jim, we—we can't leave the supplies! The sleds!"

"Sleds be damned!" Jim exclaimed in an ecstasy of excitement. "This is better than a hundred sleds! Do you want to find your radite or don't you? Are you going to M'Tonak or not!"

Hesitantly, Conley entered the strange craft. The others glanced nervously, then quickly followed, as though not wishing to be left alone.

"I—" Conley began doubtfully.

That seemed to be a signal. Instantly a well-oiled metal door slid shut behind them. Motors began to purr gently beneath their feet. The car swung around in a great circle, and they were heading into the north.

From one of the comfortable pneumatic seats Jim watched the white unending landscape flashing past. He felt strangely exhilarated now that he was on the very threshold of his quest; for that they were being taken to the long-hidden, legendary city of M'Tonak, he did not for a moment doubt.

It had not yet occurred to him to wonder why they were being taken.

But of one thing he was sure. He said, turning to Conley:

"Why do you suppose they sent the car for us? It must be that they know whenever anyone is approaching M'Tonak! Always! Other expeditions must have reached here in the same manner, else why were they never found by the men who came later?"

Conley nodded soberly. "And that must mean that, once inside M'Tonak, men are unable to leave."

IV

It seemed minutes later, but it might have been hours, that Jim Landor sat up with a start, aware that the softly purring motors had lulled him to sleep. He wondered how long they had been travelling. Now their speed seemed to have diminished considerably.

But something else seemed strange.

He turned to the tiny window, and was startled to see no more Polar Cap, no more expanse of white ice. Instead they were in a strange dark place. It was several seconds before he could adjust his eyes sufficiently to see that a wall was very close. It seemed to be moving backward and slightly upward. He knew then that they were descending somewhere at about a thirty degree angle.

"When did this begin?" he asked, turning to Conley.

"About twenty minutes ago. We must be a mile below the ice by now."

So M'Tonak lay somewhere beneath the Polar Cap! That was why men in ages past had been unable to find it, until it became a legend on a par with Earth's lost Atlantis! Jim tensed in his seat now as he thought of all the conflicting reports he had heard about M'Tonak; vague questions crossed his mind to which there were only vaguer answers.

Now the passage through which they sped seemed to widen. Simultaneously they were in a sea of softly diffused, pale greenish light. This light increased as they went on, but did not become intense or glaring; rather it seemed to permeate the very atmosphere from some subtle, unknown source. Then, with breath-taking suddenness they burst out into a vast open place and looked upon the city of M'Tonak.

M'Tonak lay in the center of a vast, shallow bowl several miles wide. In the first start of amazement Jim thought they must have somehow emerged again upon the planet's surface; but this thought was immediately discarded when he gazed across at the opposite horizon. It was concave rather than convex, which meant they were in a cavern of inconceivable dimensions. Far overhead he saw something vague and misty that must have been a roof. That soothing green light was everywhere but he still could not determine its source, it simply seemed to exist.

Now they were gliding gently down into the city which consisted of low-structured, white-marble buildings of peculiar architecture. Wide, empty avenues stretched away in a perfect geometric pattern.

"This city must be inconceivably old!" Conley gasped. "There's no other architecture like this anywhere on Mars!"

Their car was slowing now. It came to rest in a wide circular plaza. The door slid smoothly, invitingly open.

Jim glanced at the others who made no move to leave. He didn't blame them for not moving, for there was something strange and devilishly pre-arranged about all this.

"End of the line!" he said with a jocularity he did not feel. He moved to the door and stepped out.

Instantly he was aware of a strange difference. It might have been that alien green-tinged atmosphere, as if he had suddenly stepped into another dimension. Every fiber of his being now seemed to tingle in a peculiarly delightful way. It was very slight, scarcely felt, but there was no mistaking it.

As the others stepped out Jim looked at them closely. They felt it too, he noticed—especially Kaarji. Kaarji's usually dark and expressionless face was now alight with a feverish excitement.

They looked at the radiating streets about them. All were utterly empty, eerily silent.

"Where in blazes," muttered Conley, "is the welcoming committee? We were brought here, but why? Surely the place isn't uninhabited!"

"It isn't!" Jim said in that instant. "Look. Here comes your welcoming committee!" There was a peculiar note, almost a shrillness of disbelief in his voice.

The others whirled, their combined gaze following his pointing finger across to the opposite side of the plaza.

Toward them slowly came a single lone figure. It was a Martian, of that there could be no doubt; but a Martian inconceivably old! He was stooped and withered, he leaned heavily on a stout cane, but he moved forward briskly for all of that. There was a certain purposefulness about him.

He stopped before them, and leaned forward with both hands on top of his cane. His chin almost rested on his hands as he peered around at them. None of the men moved or spoke. Jim, who was nearest, was fascinated by that grayish leathery face criss-crossed with thousands of tiny lines, in which were set, like jewels, four unwinking black eyes incongruously bright and alert with cunning. There was an uncanny aura of evil about this bent little Martian, an evil made audible as he spoke:

"There are only four of you—and one Martian. Strange, I thought there were more. But it is all right. Four Earthmen, intelligent Earthmen too. Earthmen are always welcome here."

He pointedly ignored Kaarji and turned his eyes upon Jim. Then he chuckled, as though with secret glee. It was a dry metallic wheeze that reminded Jim of an empty rocket tube when the fuel is burned out. Jim was glad of the comfortable weight of his electro-pistol in his pocket.

"My name is Jim Landor," he said. "Who are you, and why were we brought here? Did you have anything to do with it?"

The old Martian gave a quirk of a smile as if faintly amused by Jim's impetuosity. But he answered the questions promptly and in order.

"My name? It is Bhruulo. Here I am the Overseer—the Co-ordinator—call it what you will. As to why you were brought here, did you not seek M'Tonak, as have innumerable men in ages past? Now you have attained M'Tonak, and you should thank me. Yes, it was I who sent the surface car for you. I send it for all men who come far into the Polar Cap."

"You still haven't explained why we were brought here."

"That," Bhruulo said with a tinge of sarcasm, "I am sure you will learn from the others far better than you could from me."

"Then there are others here!"

"Yes, there are others. You need not fear, you are free to come and go here as you please. I give you—M'Tonak! But you will excuse me now, I must leave you. I am sure you will find—the others." With that, the old Martian whirled upon his cane and hurried across the plaza in the direction whence he had come.

"Wait a minute, lad," Conley put out a restraining hand as Jim leaped forward. "Let him play his game for the time being. Let's see where his hangout is, so we can find him later."

They watched as Bhruulo, without a backward glance, entered a columnaded building that was different from the others by reason of its imposing height. Jim nodded and decided to remember that building.

"Now, Jim, let's find those others he speaks of. There are other Earthmen here, I'm convinced of it now." Conley had begun to lose his skepticism of M'Tonak—now that he had found it!—and his eyes were agleam with a growing excitement.

But search as they would, they saw no other occupants. They traversed streets that were dead and empty and silent. That palely diffused greenish radiance was everywhere, coloring all with a ghostly brightness. For several hours they explored, wandering far from that central plaza.

Kaarji stayed very close to Jim now, his original excitement having faded; indeed he seemed appalled, if not a little frightened, as he stared around in the abysmal stillness, and several times Jim noticed the Martian pass his hand in a puzzled manner across his brow.

Wessel's mien brightened, as he watched the needle of his radite-finder gyrating wildly as if at any moment it would jump its bearings.

"It must mean we're now in the very center of the main deposit!" he exclaimed. "If only we—"

It was then they saw the figure of an Earthman emerge from a building hardly fifty yards away. He saw them at the same time. He turned quickly indoors again, and shouted something that sounded like: "New arrivals!"

Then three other men emerged, and they all walked toward the little group of five.

"We're friendly," one of them said as they neared, and Jim's hand fell away from his weapon. "Because we have to be, here. Hmmm. When did you arrive?"

"A few hours ago."

"Uh-huh. And you met the funny little man, I suppose?"

"If you mean Bhruulo," Conley said with a grimace, "we sure did! Is he head man here?"

"More about that later. My name's Spurlin. Ross, Fleming, Adams," he introduced the others.

Jim was staring at the speaker, a huge man with a purposeful set to his unshaven jaw. "Then you're Gregg Spurlin, who headed the scientific expedition three years ago in the search for M'Tonak!"

"And found it, as you can see. Found it too damn well. But we weren't the first. What about you?"

Briefly, Jim told of their trek, and of his search for his brother. "What about him?" he said in imitation of Spurlin's own brusqueness. "Frank Landor. He should have arrived here weeks ago, unless—"

He stopped there, looking from one to the other. The men were looking uncomfortably at each other.

"No Frank Landor ever showed up here," Adams said.

Fleming nodded agreement, a little too hurriedly, Jim thought, and none of the men would look directly at him.

"They're lying to you," Spurlin said. "You might as well know the truth; but before I tell you about it let's get back inside, out of this green hell."

He led the way back into the building whence they had emerged. But once inside they did not stop. The greenish radiance penetrated even there. They hurried over to a wide metal door that slid silently open when Spurlin pressed a hidden button. Revealed to their gaze was a dark narrow tunnel, leading downward.

"What about the Martian?" Ross said, addressing Spurlin.

"He goes along!" Jim snapped, and Kaarji looked at him gratefully.

"All right," Spurlin murmured softly. "No harm if he comes. But I don't think he'll last long, no Martian ever does in this city."

If Kaarji heard the words he did not show it, as he followed Jim into the tunnel.

"About your brother," Spurlin spoke brusquely out of the darkness as they moved along. "Yes, he arrived here all right. For a while, Frank Landor was with our secret little group down here below. But—there's something about that greenish atmosphere, something exhilerating but also deadly, in a very subtle and insidious way. Sometimes it increases, penetrates even down to us, through walls and things. But there are some men who—"

"Yes, I know," Jim's voice was as dead as the hope within him. "Frank was one of those men. He couldn't stay cooped up here. He was curious, he had to find out—things, and the reason for things. That what you're trying to tell me?"

"That's about it. Like others who have come here he had to go up into the city, searching, trying to solve its secret. Every day he and a few others went up. Always they returned to us here, exhausted, until one day—they just didn't come back."

In silence they continued along the winding passage. Jim was thinking of his brother now, with a dawning realization that he would probably never again see him alive. He was thinking of other things too. Of that menacing greenness in the city above. Of Spurlin who seemed so calloused and unconcerned. Of the legendary emerald of M'Tonak, the lure for countless men in ages past.

Spurlin's voice shattered the silence. "Here we are." Now he was flashing a tiny light upon a massive metal door. And Jim's heart leaped, for he saw it as a metal new, and yet not new to him. It was the same dull, greenish-gray metal as the piece Kaarji had given him. Jim passed his fingers lightly across it to make sure, but said nothing.

For more than any of these things he was thinking of a bent and shrivelled old Martian named Bhruulo, who had chuckled with a secret evil glee.

The door swung ponderously open. They stepped into a huge oval room, and many men came hurrying toward them. The walls of this room, Jim noticed, were of the same peculiar metal.

"Introductions later," Spurlin said, as the men came crowding around. "Right now I want you newcomers to see the work we're engaged in here. You look like the sort who can help us in the job."

He led them to another room where a long, skeletal shape was under construction. It rested on curved cradles, pointing upward. Only a few outer plates had as yet been put into place, plates of the same strange metal Jim identified with everything here.

"A spaceship!" he exclaimed unbelievingly. "But—why a spacer here, so far beneath Mars' surface?"

"A spacer it is, Jim Landor. One such as you never saw before, and it's being built under conditions such as you cannot imagine. We have to mine and fashion the metal in the few tiny furnaces we have here, and it's inconceivably slow due to the scarcity and crudeness of tools. We've been at work on this one spacer for three years.

"As for this new metal, it's to be found here in huge deposits. In some ways it's like radite, it might even be radite, strangely changed through the centuries by those peculiar green radiations. Anyway, it's amazingly light and tough, almost expansive under fuel pressure and it's going to revolutionize spacer construction if we can only get any from here and make it known!"

"But how, man? How do you propose—"

"To get the spacer out of here?" Spurlin smiled confidently. "In one super blast we're going to hurl through this roof to the city above, and through that cavern roof onto the surface of Mars. I'm fully convinced this metal is capable of withstanding it. We're building a double hull. And we have enough fuel hoarded here to take us clear to Earth if we wish."

Jim nodded, but he was not enthusiastic. "How long, do you think, before you finish it?"

"Perhaps only another month now! The ore's damnably hard to get out, and we can only stay up there on the surface a few hours at a time—but with the added help of you new men...."

"We're with you to the finish!" Conley exclaimed, and the others nodded enthusiastically. Wessel, especially, had listened with an eager intentness to Spurlin's description of the new metal. Wessel had come seeking new radite deposits, and had stumbled upon something vast beyond his fondest dreams! Even his loyalty to TRI-PLANETARY MINING was fast beginning to waver.

"What I want to know," Jim voiced the thought uppermost in his mind, "is the status of that little old Martian, Bhruulo."

Spurlin frowned. "No one seems to have found out, and most of us don't care. He's incredibly old, of course. He seems to have been here always. In some strange manner, he seems to know when men come into the Polar Cap, and he always sends that surface vehicle out for them. However, he completely ignores us here. I'm not even sure that he knows we're working on this spaceship! We try to keep out of his sight, and I've personally not seen him more than twice in the past year."

"But isn't it incredible that in three years he hasn't found out or guessed what you are doing?"

"Not so incredible. We don't know what he's doing. We leave him alone and he leaves us alone."

"But," Jim exclaimed unbelievingly, "he brought you here, and you're not even curious to know why?"

"Let me remind you that certain men have been curious—and they have disappeared. Anyway our sole purpose now is in completing the spacer for our escape."

Jim gestured disdainfully. "And you, Spurlin—you once claimed to be a scientist! You have not even the scientific mind—"

"One's mind," Spurlin interrupted softly, "somehow, does not seem to be the same after three years in this place."

"All right. But before I leave here I'm going to find out what Bhruulo's purpose is! I don't like the way that old Martian grinned at me. He's got something up his sleeve, and I think you men'll find it out too late."

Spurlin smiled sadly. "All right, Jim Landor. Each man is his own boss here. At least I wish you would accompany a few of us tomorrow. We're getting more of the metal out, and trying to determine the proper spot to blast through with our spacer. You'll become more acquainted with the city and the general terrain, and maybe it'll change your mind."

"Sure, I'll go," Jim agreed. But he didn't think it would change his mind. He had wanted to find M'Tonak, here he was in M'Tonak and he was gong to solve the mystery of M'Tonak. More than that, he was going to learn once and for all what had happened to his brother.

V

The following day a dozen men ventured up into the city. Spurlin seemed disappointed as they stepped out into the street from their secret building. "Not an ideal day for it," he commented gruffly. And at Jim's querulous look, he explained, "Those emanations seem stronger today. I give us only two or three hours, at the most."

They went into the rocky terrain beyond the city, toward the near horizon where the cave roof tapered down. That was hardly a mile away. Jim found it hard to believe that over their heads was the Polar Cap, vast and desolate. Glancing up, he barely made out the dim contour of their roof; and it suddenly occurred to him to wonder what sustained it, why it didn't collapse under that tremendous pressure of rock and ice!

He knew why, only a minute later. There came a sudden, smooth hum in his ears. The very air around them seemed surcharged with energy, or rather all energy seemed to be rushing away from them!

"This way!" Spurlin exclaimed, making a hasty detour from the spot. Barely a hundred yards away Jim could discern a vague swirling mistiness, in the form of a huge column that reached up to touch the roof. Suddenly, he knew what it was, knew also that it would be death for any man who ventured too close.

"Ionization zone." Spurlin voiced Jim's own thoughts as they hurried in the detour. "An electronic tower of strength! There are usually six of them in a straight line across this cave, but once in a while new ones spring up out of nowhere. I think Bhruulo controls them."

Jim nodded uncomfortably, and tried not to think what would happen if all those electronic zones failed, with millions of tons of ice above them.

They reached their objective at last. Tunnels were in evidence where the men had been taking out the ore. They resumed work at once, but it was slow and heart-breaking. Their tools were crude, and the ore was the most difficult Jim had ever handled.

Wessel worked harder than any of them, his eyes agleam with a new excitement. "Look at that stuff," he said once to Conley. "Over fifty per cent pure content, most of it!"

It was perhaps an hour later when Spurlin called a halt. "Enough for today. We'll try again tomorrow."

Jim didn't need to ask why they must stop. Already he felt that strange tingling in every fiber of his being, which increased as the minutes passed, and he knew that here was a dangerous thing.

"We have so little time in which to work up here," Spurlin said as they hurried back. "Do you see now, Jim Landor, why it's taken us close to three years?"

Jim saw, indeed. Within him there surged a vast admiration for these men who had persevered in the face of almost insurmountable difficulties, to build their spaceship from the barest resources around them.

Yet close upon this there leaped to Jim's mind another thought, unannounced and without reason. It was simply a feeling that there was something vastly, terribly wrong with what these men were doing! It was more than a feeling, it was a certainty! It didn't make sense—that they shouldn't escape from M'Tonak—but now Jim knew it!

Before he could think long upon it, however, they had come in sight of their building and Jim saw a familiar figure emerge. It was Kaarji, but there seemed something vaguely wrong with him. He looked in their direction but seemed not to see them at all, as he turned and walked away with a long, purposeful stride.

Something struck another ominous note in Jim's brain. The men reached their building and entered it, but he did not stop. He hurried after Kaarji.

"Landor! You damn fool, come back here!" Spurlin cried after him.

But Jim waved a hand, not looking back. He hurried after the Martian. Those emanations were almost unbearable now, but he didn't seem to mind. There was something ominous about them, but something else as well that he could not resist.

He had miscalculated Kaarji's distance, however, because somewhere in the maze of streets he lost him. But he knew where the Martian was going—where they were both going. Hours later it seemed, but could only have been minutes, when he came in sight of the imposing edifice where he had last seen Bhruulo disappear.

Now he hesitated. His mind was crystal clear, clearer than he had ever known it before. But somehow it did not seem to be his own. He struggled a little, but the result was inevitable, he seemed to know it. He gave up almost voluntarily. He continued toward the building and entered its portals that were open wide and waiting.

He faced a long, greenish-gloomy corridor of marble. With hardly a pause he continued along it. Tall imposing doors, tightly closed, were on either side of him, but he gave little heed to them. The corridor turned sharply once, and then again, and then it seemed to lead a little downward. Jim could not be sure. He only knew that he was being led somewhere, that he was to face something. A cold fear caught his brain, but he could only go on.

Now the corridor walls seemed to waver, seemed to swim beneath a sort of radiance. But it was a glaucous radiance, ineffably green as the light beneath the waters of a shallow sea. It increased in intensity, however, as he went on. It became almost tangible, it beat against him, it seemed to pluck with evil intentness at the fibers of his mind. Jim laughed once, laughed wildly, but did not pause in his stride.

The corridor made one more turn and then he was walking into a light so blinding that it staggered him momentarily. It flared up once in a great greenish effulgence, then died down into a steady pulsation. Now, Jim knew, he must be approaching the very source of that all-pervading light which had so puzzled him since his arrival at M'Tonak.

But now he had a vaguely uncomfortable feeling. It was as though a million eyes were watching him, observing every move. It was as though a million tiny fingers were tearing away the shreds of his mind with secret, silent amusement. Jim did not look about him as he walked on, for he knew no one was there. It had something to do with this light, that much he knew.

Now he could see the end of the corridor through the pulsing greenish haze. Something seemed to be there, something towering and opalescent—and waiting.

He came very near before he saw what it was, a huge circular glass-enclosed well that towered up to the ceiling fifty feet above. It was from this well that the light came. Jim could see the gentle pulsing of it, with streamers of a darker color flashing through it vertically.

Those millions of eyes now were very near. Those millions of fingers probed into his brain unbearably. Jim pressed his hands to his throbbing temples, but the pain continued to expand within his skull. He could not turn and flee, for something held him there. He tried to cry out against it, but his throat seemed to contract and no sound would emerge.

He had no knowledge whether it was minutes or hours that he stood there; but when at last he felt his legs giving way beneath him, and glimpsed the blur of the floor rushing up, it was with a profound sense of gratitude for the oblivion that would be his.

But this was not to be. No sooner did he feel the floor beneath him, than the force which had beaten him down partially withdrew. Jim staggered to his feet, weak and a little dazed. Now something else was happening behind that glassite-encased well. The green pillar of light was lowering, coalescing upon itself with a slowly swirling motion.

And then, as the tower of light lessened, Jim saw what rode atop it. He saw a shape, huge, iridescent and apparently weightless. It seemed at first simply a larger area of greenish light, but for a single second he glimpsed more. He saw the massive core of it. He felt his stomach turning over in a prodigious yawn, and his brain churned in chaotic horror.

The thing he saw was a roughly globular, quasi-amorphous shape that was in a state of constant fluxion. It was partly tentacular, it writhed and pulsed, it seemed to project itself at will. Darkish tendrils came uncurling from it as if it were reaching for something not quite attainable. Simultaneously it spun slowly atop its pillar of light which seemed also a part of itself, somehow. It was alive, a thinking, intelligent entity. That much Jim knew. It would even have been an entity of beauty, with its whirling greenish effulgence, were it not for one thing.

It was evil. Terribly, undeniably so. Jim could feel the impact of it almost physically. Almost he felt that here was the essence of all the evil of another universe, compressed into that one horribly writhing mass that was now trying to expend itself but could not. And he had the feeling that although it could be moved to terrible, devastating anger, it was now for some reason gleeful.

It came riding down, light as a feather atop its light, until it hovered just a few feet above Jim's head. Jim knew that he was being examined microscopically, perhaps even fourth-dimensionally. He shivered a little. He tried to take a step back but could not. There came a sudden chuckling within his own brain, and then mentally he heard the entity speak.

"Yes, Earthman, you were right in your estimate of me. I am 'evil' to such as you. At least that is what Bhruulo tells me, and I have come to believe Bhruulo."

Jim crouched before the thing, staring up at it. He still felt its probing mental fingers in his mind, and the fingers were ... unclean. He spoke aloud at last, in a voice he hardly recognized as his own.

"What—what in heaven's name are you?"

There came that chuckling note again, as the thing spoke.

"Whatever I am, Earthman, it is not in heaven's name. I do not exactly know myself what I am. I personally have no conception or remembrance of how I came here. I only know what Bhruulo has told me. It pleases me to tell you."

The mental voice ceased abruptly. Then sudden, vivid pictures flashed stereoptically across Jim's brain and were as quickly gone. He saw a city he recognized as M'Tonak, and the city was teeming with people. Jim knew that must have been many, many years ago.

The scene changed. As through another's eyes, he caught a blurry vision of this evil entity flashing from out of the sky to land near the city. He felt some of the consternation and then horror as the populace died by the score in the streets. There was no apparent reason except the presence of the alien thing. Just to look at the blinding brilliance of it was to die. Jim caught confused pictures of all available weapons being rushed to the scene to do battle with the thing, but to no avail; as the M'Tonakians died, the entity grew tremendous in proportions and in power.

These pictures flashed away and Jim saw others; the last few scientists of M'Tonak, in a barricaded place where they worked frantically on a weapon with which to battle the alien thing. They completed the weapon but they could not destroy the entity. After a terrific struggle they subdued it temporarily by means of certain rays and beams. In this manner they at last brought it into captivity within the glassite well.

"Bhruulo says all this happened hundreds of years ago," the voice came again within Jim's brain. "He is the last of that final group of scientists who subdued me. I have only a vague remembrance—"

"Bhruulo says!" Jim gasped, struggling with the significance of the idea.

He looked up and saw the spherish, effulgent thing spinning with silent amusement. "Is Bhruulo's longevity, then, such an unusual thing? I do not know. Your time-scheme means little to me. Perhaps Bhruulo's great age is due to his perpetual proximity to me, I only know that, unlike other Martians and Earthmen, he is immune to my strongest powers now."

Jim sensed a certain bitterness in that mental voice, almost a hatred for Bhruulo. Looking up at the greenish, brooding globe, Jim ventured a daring question.

"Don't you sometimes long to be—free again?"

He felt the tendril-fingers grasp his mind again with a fierce tenacity. He cried out against the physical pain of it, but even through the pain he heard the throbbing answer.

"Free! Yes, Earthman! Bhruulo glories that he has me trapped here. Often I remember those olden days when I almost conquered the city of M'Tonak and the planet Mars! Bhruulo has promised me those days again, and much more. He says he is preparing for it, but I do not know what he means. I only know that I tire of waiting!"

There were more mental words, but Jim only heard them through a mist about his brain. He knew that here, at last, he had solved the mystery of M'Tonak! This evil entity from out of another universe or another dimension was the "emeralds" of M'Tonak which had lured men up here in ages past for its own, or Bhruulo's, devilish purpose. But what was that purpose? Something vastly imminent, Jim knew! Perhaps it was something the entity even now was trying to tell him in its strangely confidential mood.

"That is enough. You have said enough! I have warned you about this!"

That was not the thing's mental voice! Jim knew it, even as he whirled to face Bhruulo who had come from nowhere to stand behind him. Bhruulo was furious. His grayish, lined face was a mask of hate—but not for Jim. He hurried forward like a scuttling crab, supporting himself on his cane with both hands. He approached the glassite barrier, and began to manipulate tiny wheels there which Jim had not noticed before. A network of wiring led down to several complicated box-like affairs set in the floor.

Then a very curious thing happened. If a writhing, pulsing, spinning globe of evil can cower, that is what the entity did! No sooner had Bhruulo's hands touched the wheels, than the entity sank down to the floor, then darted frightenedly up again, to cringe against the furthermost confines of its prison. It poised there, hesitant, as if watching Bhruulo. It ventured out from the wall and then back again. It hardly pulsed at all now, as if holding its breath in fear.

A tiny hum came from the machinery Bhruulo was manipulating. It rose to a shrill whine and then passed beyond the audible. A sudden criss-cross of pencil-thin beams leaped about the confines of the well. They were pale, scarcely visible, but Jim sensed the power of them. He heard a mental shriek of agony from the spinning globe, then it was tumbling up the sides of the well, out of range. It vanished fifty feet overhead, in a haze of greenish light.

Using his cane as a pivot, Bhruulo pirouetted slowly to face Jim.

"Now," he said, "we can talk to each other without interruption from that thing. Too bad that it hates me and I hate it. For we need each other.

"I do not know," Bhruulo continued, "how much the Dim-Ing told you of itself or of me and my plans. It does not particularly matter, now."

"Dim-Ing?" Jim repeated querulously, trying to focus his mind again.

"Yes. 'Dimensional-Thing.' Facetious? I have my moments of humor. It has only a dim remembrance of its past before it came to Mars; but through certain conversation with it I have come to the conclusion that it somehow had birth in another dimension impinging delicately upon ours. How or why it was flung across to us we shall never know. But it is nearly finished on Mars."

Something caught at Jim's brain. He started a little.

Bhruulo laughed shrilly.

"Yes. Had you not guessed before? The Dim-Ing feeds upon the minds of men. Oh, very subtly, of course. But for the presence of such sustenance on Mars it would have died long, long ago. At first the accumulative mental sustenance of Mars was more than sufficient. I was careful to keep the Dim-Ing under my control, even as now. But as the years passed—more years than you think, Earthman—I saw what was happening. We were hastening the eventual decease of the Martian race! The Dim-Ing absorbed, at first, all evil from the total Martian mind. And then—even more.

"No doubt, Earthman, you have read something of Martian history. You will remember that several centuries ago a frightful war raged across three major continents of Mars. Almost abruptly, that is to say within the space of a few years, it ceased mutually and without apparent reason! It was the Dim-Ing and I who indirectly caused that. Then, you will remember, there came an almost Utopian state for something like a few score of years. It quickly passed as the Dim-Ing sent out its subtle radiations almost desperately, across the surface of Mars. The Martians became the inactive, indolent, dying race you see now. In the last few scores of years, sustenance for the Dim-Ing has been meager indeed."

Jim only stared at this Martian who according to the entity was hundreds of years old. A horror crept into Jim's brain, and a subtle warning. Here, he knew, was the one to be guarded against. Here in this bent little Martian was the ultimate evil. His was the controlling hand.

Jim had been listening in a slowly dawning horror. Now he found his voice at last, as he took a single tense step toward Bhruulo.

"And you—you tell me this! This thing that has been happening to the Martian race! You, yourself a Martian—"

Bhruulo did not move and the expression on his face did not change.

"It is not what I am, or once was, that matters. It is what I shall be. With the tool that I have now, immortality lies within my grasp. That, and eternal power. I shall continue.

"Within the last fifty years, you Earthmen came. I need not say that you were a Godsend. The Dim-Ing was at a very low ebb indeed.

"Even at the height of their scientific accomplishments the Martians never quite achieved space travel. By what miracle you Earthmen achieved it shall always remain a mystery to me. But I thank you. You came when I needed you most.

"I discovered that your Earthian minds are stubborn, very stubborn indeed. The Dim-Ing likes that. It can subsist much longer on an Earthian mind than on a Martian. Furthermore, I learned that the Earthian mind is curious—one of the inherent qualities of your race. Therefore, I embellished somewhat the existing legend of M'Tonak. And you all came searching greedily; if not in droves, at least, in sufficient numbers.

"And now you are building a spaceship for me. I have known it all along! I have brought you here for that purpose! I know it is very near completion, this spaceship which shall carry, not Earthmen back to Earth, but the Dim-Ing and myself."

"But it shall not!" Jim had let Bhruulo talk on, knowing what was coming. In his mind now was no room for horror; his mind was quickly alert and his hand was even quicker, as it flashed to the electro-pistol in his belt.

But Bhruulo made a motion too, so fast that, paradoxically, there was a certain casualness about it. He still smiled. He raised his cane on which he had been leaning with both hands. From a lens-covered bore in the end of it came a thick whitish light, touching Jim's hand and holding it motionless. It expanded, enveloped all of his body so that he could not move.

It surged a little upward, full into his face.

Jim Landor crumpled noiselessly and lay still.

VI

His mind came surging slowly back up from the dark depths of nightmare. His head ached unbearably. He had thought an insistent, warning voice was crying out at him. He opened his eyes. This was no nightmare, for memory came back in a rushing flood, and he still heard the voice, low and warning and very close to his ear.

"Do not move, Jim Landor. Do not say anything, just listen. This is Kaarji, I am here close by you."

Kaarji! Jim had almost forgotten about Kaarji. Then he took the warning and tried not even to think, he just listened, in a detached manner.

"We are in a room off the corridor. That Dim-Ing thing is only a few hundred feet away. I hope it has not contacted your mind again, for I have something important to tell you. It is a good thing you followed me here so closely, for the Dim-Ing withdrew its concentration from me and centered it on you. Thus I was able to slip past this place, and I explored a little. Jim Landor, below these corridors I have discovered a huge room full of machinery. I cannot understand it all, for I have not a scientific mind; but I thought if we could escape from here, and I could take you to this place—"

Slowly, Jim allowed his mind to relax. He felt no more of the probing mental fingers in his brain.

"It's all right, Kaarji, we can speak freely now. I suppose that's where Bhruulo caught you, in that secret room?"

"Yes. It seems to be his living quarters as well."

"I think I know what that machinery is, Kaarji. It's vital to the existence of M'Tonak. If only we can get back there—"

Jim rose to his feet and looked about the room. It was small and empty, the walls were of marble. He walked over to the single door leading to the corridor. He tried it, and to his surprise it opened easily!

But he staggered back as from a violent physical blow, as the radiations from the Dim-Ing lashed against him.

"Hum, our little playmate again." Jim rubbed his half-blinded eyes. "Clever devil, that Bhruulo. He knows that no man could escape through that. He was so sure of it that he didn't even remove my electro-pistol from me."

As the pain passed from his eyes, he removed his pistol and felt the comfortable weight of it in his hand; but he thrust it back into his belt again, knowing it was useless against the Dim-Ing. Then an idea struck him like a thunderbolt.

"Kaarji, we may walk from this room yet! I have one weapon that Bhruulo hasn't counted on, and that is—the Dim-Ing's hatred of Bhruulo!"

Hurrying to the door again, he opened it infinitesimally. And he leaped back to the furthermost confines of the room as the Dim-Ing's thought-emanations came flooding inside, in a gentle greenish haze.

Jim centered all of his mind, now, on the one all-important thought. "Bhruulo! I shall kill him! He thinks he will keep me here and feed my mind to the Dim-Ing—but somehow I'll escape from here and kill Bhruulo. I swear it!" He strove to arouse an overwhelming hatred in his mind for the ages-old little Martian.

The Dim-Ing's power surged anew.

He felt the alien entity's mental fingers grab hold of his mind again. He stifled the rising exultance and reiterated his resolution to kill Bhruulo. Now he noticed that the Dim-Ing's mental presence was expanding through the very marble walls themselves. As never before, he began to appreciate the potential power of the thing. But with an effort he repeated his oath to kill Bhruulo; it became now not so much an oath as a promise, for he knew the Dim-Ing had tightly grasped his mind and was listening.

It was easy. So ridiculously easy that Jim should have been suspicious, but was not.

"If you mean it," the Dim-Ing spoke to Jim's mind at last. "If I thought you really would—"

"I mean it!" Jim flashed the thought fervently. "Let me out of here and I will rid you of Bhruulo, once and for all!"

He almost laughed aloud.

Slowly, hesitantly the thing's mental barrier was fading away. Jim stepped to the door and opened it widely. Nothing beat him back now. He motioned to Kaarji, who followed him almost frightenedly out into the corridor. There the mental power of the Dim-Ing was a little more in evidence, but not enough to stop them. It was as though it were watching....

"This way," Kaarji breathed at last. He led Jim in the opposite direction from the Dim-Ing, then into a cross-corridor that extended interminably. At last they reached a door that opened onto stone steps leading downward.

"Careful," Kaarji warned as he led the way slowly.

He didn't need to warn Jim. The latter was wary as never before, and he kept a hand always near his electro-pistol. Something was vaguely wrong about all this but he didn't know what. For one thing it seemed too easy.

At the bottom of the steps was another sliding door. Kaarji paused before it and whispered, "This is the room!"

Jim stood still, listening. There was no sound from beyond that door. The silence was a vast womb about them, menacing. Jim slid the door noiselessly open; they stepped inside and stared around.

They saw huge circling tiers of peculiarly constructed dynamos. They were in operation, Jim knew that, for he could feel a certain surge of power even though there was no sound. A bewildering network of cables led from the dynamos to a central, predominating machine that towered fan-like above them all. It was this electronic tower, he knew, that created the swirling pillars of strength that surged upward and outward to support the vast cavern roof overhead.

Then they saw Bhruulo. He was in a little glassite room at the foot of the electronic tower. Tiny wheels and dials were banked around him, and he was busy making delicate adjustments. So busy that he didn't see them standing just inside the door.

Now Jim heard the insistent voice of the Dim-Ing in his mind again: "Kill him! Do it at once! Do as you promised...."

Jim didn't need the prompting voice, but he wasn't going to ray a man down from behind; besides, he doubted if his beam would penetrate that glassite cage. He stepped quickly to one of the dynamo stanchions, and drew Kaarji down beside him.

He waited, despite the Dim-Ing's impatience that he could feel seething within him. Bhruulo finished his adjustments at last, and stepped out of the cage. He was still a good fifty feet from Jim. He turned, to go deeper into the maze of machinery.

Jim arose and said quietly: "Bhruulo!"

The aged Martian whirled with amazing agility. Jim saw the look of incredulity that leaped into his eyes. Bhruulo leaned heavily forward, his two hands gnarling about his cane. Then his lips quirked into a toothless smile, and he started to say something.

That was to throw Jim off guard. Simultaneous with his speech he lifted his hands lightning-like, and the cane levelled. But Jim was expecting that. With a single sinuous movement his pistol was in his hand, its bluish beam was pencilling out. It caught Bhruulo squarely in the chest before he could press the button on his own weapon. He staggered forward, his cane-weapon sagged; he tried to level it again but could not. Still he staggered forward, hatred mingled with horror in his eyes. With amazing strength his spindly legs carried him across the room, as he mouthed unintelligible Martian words.

The electronic beam caught Bhruulo squarely in his chest.

Jim fell back a step. He hoped Bhruulo would not find strength in his arms. Would that damned Martian never die? Jim knew his beam had bored a hole clear through the creature's chest; he could see the blackish blood oozing from it. Jim felt a cold horror gnawing at the pit of his stomach even as he aimed carefully and the electro-beam flashed out three more times. He saw three more holes rake across the Martian's chest.

Bhruulo fell with a crash right at Jim's feet, and the cane clattered from his fingers. Even the mask of death could not erase the hate from those ebon eyes as Bhruulo stared lifelessly up at him.

Jim shuddered once, then reached out with his foot and turned Bhruulo over so that he lay face downward.

He was aware of Kaarji standing beside him, and Kaarji saying quickly, tensely: "Jim Landor! You remember when I said that this time I should not return from the Polar wastes? This is what I meant, I know now what I must do. But you must hurry, get back and tell the other men, or none of you will ever leave M'Tonak!"

Jim stared at him uncomprehendingly, trying to listen at the same time to Kaarji and to the jubilant voice of the Dim-Ing that was surging in him again.

"Kaarji—what do you mean?"

"I mean, Jim Landor, that I know the intentions of the Dim-Ing! I know at last what has happened to my race and what might happen to Earth. But it shall not happen!"

Kaarji leaped toward the glassite cage at the foot of the electronic tower. In a few strides he was there, had hurled himself within it and barred the door behind him. His eyes were glowing and purposeful, as he stared out at Jim who came running.

"You had better hurry, Jim Landor, and warn the others. Do not try to stop me, for I have a feeling this cage is impregnable. In a very short time I can wreck these controls, the electronic zones will cease and the entire cavern roof will collapse under the pressure of millions of tons! Get back to the others and escape from M'Tonak."

He turned deliberately and examined the controls banked around him. He reached to his pouch of tsith stems, and placed a few of them in his mouth before he continued.

"I suggest you try to distract the Dim-Ing's thought as much as possible, so it won't center on me here. I will try to hold out for half an hour at least, longer if possible. But hurry!"

Conflicting emotions swept across Jim like a flood, but were beaten down by the cold realization that Kaarji intended to carry this thing through without compromise. The Martian would destroy all of M'Tonak, including the Dim-Ing and himself, in an endeavor to save Earth from the thing that had happened so subtly on Mars.

Jim whirled, started to race away but turned back. "All right, Kaarji. Thanks seems a pretty feeble word for what you are doing, but if I get back to Earth I shall see that you are never forgotten for this. Now give me the rest of those tsith stems—I have an idea!"

Without question Kaarji opened the glassite door, and tossed out the pouch of stems. Jim snatched it up and raced away without a backward glance. He hurried from the room and up the stone stairs to the corridors again.

There the Dim-Ing's power struck more forcefully into his mind. It seemed somehow diabolically gleeful now. But Jim hurried on, hurried toward the evil entity. Finally he stood at the foot of the towering well, and saw the spinning globular shape descend upon its coalescing pillar of light.

"You did it well," the thought came flashing. "You kept your promise. The thing I have dreamed of for ages has happened, Bhruulo is out of my way and I have a free hand! Yes, Earthman, now I see in your mind everything that Bhruulo told you. There are other Earthmen here, completing a huge ship by which to go back to your planet. That is what Bhruulo was counting on, that is what he would not tell me. He had planned to take me to Earth and there keep me under his control, as he has here. But now that you have so kindly removed Bhruulo, I can do this by myself! I need only wait until the men have completed their ship, then blast their minds to annihilation!"

This Dim-Ing was the ultimate evil, not Bhruulo! Jim had known it all along, and now he realized how he had played into its hands! A momentary panic seized him. He could picture the thing landing the spaceship on Earth's northern or southern polar ice, or in the unexplored depths of Brazilian jungle. Hidden from the sight and knowledge of men for years, it would carry on the subtle destruction of Earthian minds as it had Martian; and now, unhampered by Bhruulo, it would grow in size and potency until who could say what the end would be! Perhaps there would be no end; there were other planets besides Mars and Earth....

"Thank you, Earthman, that is a thought I will remember. But your mental pictures of the terrain of Earth were rather vague. Show me more clearly."

Jim felt the agonizing mental fingers tearing the tissues of his brain apart.

At the base of the well he saw the obscure little door Bhruulo had opened to manipulate the pale, pencilling beams. Instantly, Jim was on his knees, had wrenched it open. He did not try to work the beams, knowing the Dim-Ing could have stopped him in an instant; he merely tossed the pouch of tsith stems out into the center floor of the well, and rose quickly.

"There's an offering for you! I kept my promise and killed Bhruulo, now you keep yours and let me go!"

The entity had made no such promise and Jim knew it. But he whirled and raced down the corridor unheeded. It was only the element of surprise that would carry him through now, surprise and utter wildness. He even laughed wildly aloud as he ran on. And nothing stopped him!

Nothing stopped him until he was halfway to the outer door leading to the street. Then he felt a terrific impact, he stumbled, fell to his knees and toppled forward on his face. He arose against a tremendous physical pressure and staggered on. Again he felt that impact, as he was battered against the marble corridor walls. But with a fierce tenacity he kept his feet, and kept going.

He reached the street. His legs were heavy as if he were fighting against a hundred gravities. He felt that the Dim-Ing was merely toying with him, as a cat with a mouse. As Jim hurried on, or tried to hurry, to the place where he would find Conley and Spurlin and the score of other men, he knew that one man could not hope to stand against that awful power. But perhaps many men, in perfect mental accord....

Again he felt the strange, fierce tingling in every fiber of his being until he thought he was walking in a sluggish sea of fire. It seemed hours later when he reached the familiar building and hurried along the metal-lined tunnel where the Dim-Ing's radiations seemed a little less intense. It was with a feeling of profound gratitude that he pushed through a final door, and sank down into a soothing oblivion. But not before he glimpsed many men rushing toward him, with surprised shouts. Among them he saw Conley.

VII

Jim opened his eyes and stared up into Conley's worried face. He coughed a little on the stinging liquor the latter was pouring down his throat.

"How long have I been here?" he asked urgently.

"Just a minute or two, lad. You're mighty battered and tired, but you'll be all right now. Just rest a while."

"Rest!" Jim repeated, and climbed quickly to his feet. "None of us can rest now—there's no time! It may be too late already—but we've got to make a fight for it, if for no other reason than because Kaarji's counting on it! No, Conley, I'm not delirious." He waved the worried Irishman away. "Listen, you men! I've solved the mystery of M'Tonak, and we've got to get out of here!"

In an anxious rush of words he explained the situation, told briefly of his discovery of the Dim-Ing and what it was, and of Kaarji's avowal to destroy all of M'Tonak.

"In another few weeks, Spurlin, your spaceship would have been finished, and the greatest horror the universe has ever known would have launched itself upon Earth! It still might happen! We've got to get back out there at once, en masse, and hold that thing's attention before it discovers what Kaarji's up to!"

It had all happened too suddenly for the men to quite believe him. They looked askance at each other.

"But after three years of heart-breaking work," Spurlin said, "to give up my spaceship now! That's what you're asking."

"A hell of a lot of good your spaceship will be, with millions of tons of rock and ice heaped on it! That's gonna happen about fifteen minutes from now, or less! Man, don't you understand? Kaarji said he'd give me a half-hour—"

"It's a trick!" Wessel squawked loudly. "Damned funny that he ever got back here to us at all! He's discovered a protection against those greenish rays, he's trying to lure us all outside to our death, so he can have all this new metal for himself!"

Jim strode back to the door, pausing only long enough to cry, "All right, stay here, then, and die. All of you! If you won't help me, that means our last chance is gone. I'll die too, but it'll be out there fighting that thing to the last!"

"I'm with you, Jim. I believe you." It was Conley's voice he heard and Conley's friendly hand on his shoulder, but he didn't pause in his hurried stride back up through the tunnel. He heard other men coming behind them, following Conley's example, but he felt that it was too late now. There could only be a few minutes left.

Kaarji might even be dead. The Dim-Ing in its subtle way might have known the plot from the first. That would mean the Dim-Ing had won, for no man could ever be able to get back down to that control room.

As they reached the street, Jim felt the power of the entity withdraw a little, as if that were necessary in order for it to embrace all their minds. A sudden new hope surged in Jim, a feeling that their combined forces might be a match for this thing yet! And even as they were racing back toward the central plaza, he was evolving a plan that might work providing they had enough time.

"Spurlin! You remember that surface car that brought us all here at various times? Do you suppose you might discover its secret? There are hidden electronic motors, I believe."

"We thought of that before, but no man was ever able to get near enough—"

"You'll get there this time, we'll see to it! Spurlin, when we reach the plaza you take one man and head for that car. You spent three years building a spaceship, but now in as many minutes you've got a tougher job—you've got to find those motors and solve them and have them ready for a quick departure!

"The rest of you men, listen. I've had a few dealings with this Dim-Ing and I think I know its weakness. It's grossly egotistic! That's the angle we're going to play on, but our minds will have to be in perfect accord. I want you all to be silent, but listen carefully to my every word, and concur with me mentally in everything I say!"

Strangely those mental fingers had withdrawn a little, and Jim wondered why. There was something almost cunning about it. They reached the plaza, and Spurlin with one man hurried to the surface car on the opposite side of the square. The others, more than a score in all, stopped before the building that housed the entity.

Jim knew that there could only be minutes now.

Even as he was formulating words in his mind, he felt the Dim-Ing's faculties expand again, surge out prodigiously to envelop them all. And with it came raucous mental laughter. The thing was laughing at them!

"Steady, you men," Jim said in a quick undertone. "Get ready now." And Jim laughed in return, laughed aloud and shortly. For beneath the Dim-Ing's laughter he thought he detected a false note! He felt that it was bluffing, stalling for time! But why?

"All right," he called aloud, "you have won! You have defeated us here, but in defeat we can laugh, for this will be your last victory! You will get to Earth but there you will meet your end!" Jim felt the power of the thing reaching out in a fierce resentment, but he continued tauntingly. "You will see that the Earthian mind does not fear you, they will seek you out. We have weapons to combat you that the Martians know nothing of—you will not last long on Earth! If Bhruulo alone kept you here in thrall, Earthman can do that and much more—"

Jim had other words to say, mocking words, but he did not get a chance. The Dim-Ing lashed out with a terrible, unsuspected force. For a single second, all of M'Tonak was livid under a garish unbearable green, as the men were beaten down to their knees in a huddled miserable group. Buildings blurred and wavered and seemed to topple. The Earthmen's consciousness dangled by a thread.

"That is only a tiny sample of my power," the thought came lashing at them. "That is to teach you not to drive me to anger again."

The men rose painfully to their feet, clinging together. But Jim was exultant now. He could not have told why, but he felt that in that one supreme burst of anger the Dim-Ing had expended most of its power, and that is what he had been counting on!

"Your Earthian minds are stubborn, very stubborn. But I like that. I think I shall like Earth. Tell me more about the weapons you have there, the scientific devices you will use to combat me."

What about Spurlin? Had he failed? That single, surface car was their only escape from here! It seemed hours since Spurlin had raced across the plaza toward it.

"We're lost, Jim," Conley whispered wearily. "We're beaten...."

"Oh, no we're not!" For suddenly, strangely, the Dim-Ing did not grasp their minds any more! It was slipping away, and they felt strangely free and buoyant. But why? Why should it withdraw in its moment of triumph, just as it was learning what it wanted to know about Earth?

In an awful moment of panic Jim thought: "Did it read in my mind something about Kaarji—does it know what Kaarji is doing?"

Simultaneously, there came a shout from Spurlin across the way, and it was a triumphant cry. "Hurry up, you men! We've got these motors going, but Lord knows—"

Spurlin's welcome voice! Jim found himself pounding across the plaza, behind the others. As in a dream he could hear the smooth threnody of the motors.

And for one last time he felt the mental power of the Dim-Ing reaching out, but it was half-hearted and uncertain, it wavered a little and seemed vaguely bewildered. Jim even paused in his stride and looked back defiantly. He felt it trying once more to grasp his mind, then it fell away disheartened. Not until then did the truth burst upon Jim, and he realized what was happening!

He reached the car last of all, and dropped exhausted across the threshold, as the re-action of all he had undergone suddenly hit him. He felt hands pulling him in and other hands sliding the door closed behind him. Even then the car was moving away, gathering speed toward the single obscure tunnel leading up and out of the vast cave of M'Tonak.

VIII

Jim knew nothing more until he struggled up again from the vast depths of darkness. This time, his mind felt blessedly alive and buoyant and free. He simply lay there against the soft cushion and let the strength flow back to him.

He sat suddenly erect. He was alone, and the car had stopped. He looked out into the white expanse of the Polar Cap once more.

He hurried to the door, and was relieved to see the rest of the men gathered outside, staring at something and talking excitedly. He joined them. Conley greeted him and pointed silently.

Barely a mile to the north, from whence they had come, a great greenish display suffused the lowering sky.

"That started a moment ago," Conley said. "I think we got out of there just in time."

Hardly had he spoken, when all of the ice-capped terrain beneath the light collapsed into a vast hollow, miles wide. It happened silently, abruptly; seconds later faint rumbling shook the ground. It was final. The greenish display had vanished and only the hollow remained, as if a giant had plunged his thumb into a rotten apple.

Conley sighed and turned away. "When I think of poor Wessel and the others, buried a mile below there—"

"They got," Jim replied caustically, "just what they asked for. You'd better hope that entity is as dead as they are!"

"No doubt about that. But I can't understand it, Jim. I thought sure we were lost, when it was brow-beating us there in the plaza. What happened after that? All I remember is running for the car."

"What happened," Jim replied softly, "is that a wild hunch of mine worked. Did you ever indulge in Martian tsith stems, Conley? It's horrible, vile stuff; makes anyone, except an addict, violently ill. And it hits you suddenly, like a barrage of rocket-blasts. Well, I gave a whole pouch full—Kaarji's—to that Dim-Ing! D'you know, despite it being an other-dimensional entity, it had some very human qualities? Apparently it was curious, as well as egotistic; it must have investigated and then absorbed those tsith stems, and it became violently ill—at just the right time for us!"

Spurlin had been trying desperately to get the motors started again, but to no avail. Now he approached the others with a worried frown.

"Those motors are so constructed that they can work in two ways. First, they can operate from a direct electronic beam—that's how Bhruulo controlled the car from a distance, and that's the way we've come as far as we have now. But with the destruction of M'Tonak, all the beams are gone!"

"Then you mean—we're stranded here?"

Conley pictured hundreds of miles of ice still lying before them. He remembered that the Cap had already started its break-up, and no man could ever get across it now. Not afoot!

"On the other hand," Spurlin was saying hopelessly, "the motors should work from the electronic emanations of that new metal we found. Even a tiny amount of it. But," he waved his hand to the north, "there it all lies buried and we'll never get to it in a million years!"

Defeat was in his voice.

For a moment the men milled about, looking at each other helplessly, before Jim remembered something.

"I've gone through too much," he grinned, "in the past few days to let a minor thing like this stymie me." With a feigned nonchalance, he reached into his pocket and drew forth a piece of metal. It was the rounded medallion which Kaarji had given him, and he'd forgotten until now.

Spurlin's eyes lighted, he seized it eagerly and went back to work.

Jim looked again toward the vast hollow to the north, and he spoke softly to Conley standing beside him:

"Spurlin's wrong, though. We'll get to that metal again, and Spurlin will see his super spaceship come true. It'll be a tremendous mining job, but—well, at least we know the metal's there, and it'll wait for us."

The sudden hum of the motors was a welcome sound in their ears, and minutes later they were speeding smoothly back to the south.