GIVE BACK A WORLD

Red signal lights winked on, on the white walls that surrounded the tiers of bunks there in the belly of the Sun Child. Tension sharpened. Crap and card games broke up. Last-minute checking of gear and weapons was dropped, as five hundred men of the Survey Service climbed into their bunks for the deceleration.

This would be only the second time that Terrans, surging out to colonize the planets, had reached Mercury, the Paradox World.

As he pocketed the cards, there was only a brief flicker in Fane's pale eyes, suggesting to Rick Mills that he was a bad loser at poker. But the savage glint was masked at once.

Fane's low, broad forehead crinkled. "You lucky stiff, Mills," he said with a shrug and a grin. "Well, I don't need to win money now."

Rick knew Frank Fane some after three months of journeying from Earth cooped up in a space transport with him. He seemed a fairly good Joe, some ways. He never lent or borrowed anything. That was sound policy. Or independence carried to a fault. Besides, Rick had an idea that Fane's thin face was a flexible mask, too inclined to act out the surface he wished to show, instead of revealing his honest emotions. And his sly hints, which never told very much about Mercury, seemed Satanically designed to provoke dread in less experienced listeners.

Here came Fane's great distinction. He was the sole survivor of the Martell Expedition, the one man alive who had been on the most sunward world. Six months he'd spent there. That made him an object of awe in younger eyes. It also inspired insidious doubts about him.

And the one thing that set Rick Mills a little apart from other hard young experts that had recently graduated from the Survey Service School on Mars, and who now formed most of the five hundred aboard the Sun Child, was that he had almost made friends with Fane. Curiosity, and warmth toward people had prompted the effort. And wariness before suspicion.

From his bunk across from Rick's, Fane now spoke:

"Well, here we go. Just a few more minutes. The end of book learning, eh, you guys? The beginning of experience. I wonder if all of us will still be alive inside of twenty-four hours?"

Maybe it wasn't malicious humor. Maybe it was just the brutal kind of joshing that helps to make men.

"Shut up, Fane," Rick joshed back in the tough manner that Fane seemed to like in him. "Keep on your toes yourself or you might be the first to die."

Fane chuckled. "Always the smart boy, eh, Mills? Better keep it up. Because Mercury's a crazy place. It's the planet closest to the sun. But it forgot to turn on its axis ages ago. So the dark side is colder than Pluto must be. But on the solar side your space-boots can slosh into wetness that you might believe is water. Umhm-m. Only it turns out to be a puddle of molten lead.

"Hell, you guys have always known stuff like that. So why repeat myself? When there are interesting circumstances? A push-button war fifty million years old that got put into cold storage, for instance. Dead storage. But maybe not quite dead. I wouldn't know, for sure. How about getting mixed up with that?"

Some strange jubilance seemed to possess Fane.

The retard-jets of the Sun Child thundered to check vast speed. Conversation died as, from the zero of free-fall, weight rose to five gravities, pushing the corners of men's mouths back toward their ears.

Still, in spite of the strains in his own stocky, muscular body, Rick Mills kept an eye cocked at the long, sinewy shape that was Fane, prone on taut canvas across the aisle. Fane's grimace remained reckless.

With the mystery of Mercury at hand, Rick was like his companions. He thought some of home. Minnesota. His folks. Anne Munson. Anne who was on Mars, at the Survey Service School. They could use girls for certain less rugged jobs, Rick thought of her picture in his pocket. Honeydew hair. Cool, pleasant eyes. And under her smile her scribbled, half-kidding challenge:

"Find us a world, Rick!"

Well, it would never be hellish Mercury. No place for a girl.

Rick also thought that he would have liked to like Fane if he could. Now didn't seem the right time. His veiled bragging and shows of insolence had begun to exceed the limit, even for rough men. And there were too many questions in Rick's mind now. Was Fane struggling to keep some inner elation from showing too much? What did he want from life? Wealth, maybe? Did he have a Mercurian secret that led toward what he wished to accomplish?

Rick's cold feeling found its chief source in the Martell Expedition to Mercury of a year ago. Just Martell, Jacobs, and Fane—the pilot and mechanic—in a small, long-range rocket ship.

On his return, Fane of course couldn't be evasive in his written report to the Interplanetary Colonial Board. It had been published. Rick could remember parts of it almost word for word:

"... We had gone a hundred miles into the dark hemisphere with the tractor. Martell wandered off alone. Jacobs and I found him with a hole in the back of his oxygen helmet. Falling backward onto a sharp rock could have done it. The hole let the air out of his space suit, and the cold in....

"Jacobs ended up just about the same, two Earth weeks later. Except that it was on the hot, sunward hemisphere...."

Once again Rick thought that it was a little queer that two resourceful men should fall victims to the same accident even if roasting and freezing looked like the classic ways to die on Mercury.

Rick longed primitively just then to drive his fists into Fane's narrow jaw. Was he a liar and a murderer? If so, what was his motive?

But then Rick was almost ashamed. The Colonial Board seemed to have accepted the report. And that Fane had brought the bodies of his companions, preserved by Mercurian conditions, back to Earth, was a minor hero's deed, wasn't it?

Other of Fane's written comments came back in Rick's mind:

"There is far more frozen air and water on Mercury's dark side than there should be....

"Several times I may have imagined glimpsing movement. Once I thought I saw something small scurry into hiding under some ancient wreckage. I tried to dig it out. I don't know what it was....

"There are ruins and much ancient junk on Mercury. Martian stuff. And from Planet X. As could be expected.... Left alone while I waited for favorable relative orbital positions for a return to Earth, my investigations of things on Mercury were somewhat limited, however...."

Such were Fane's sketchy notes, supplemented by a few blurred photographs that had been salvaged from much film that had been obviously ruined by a small radiation leak from his rocket's A-jets. But as for the wreckage he had written of, everyone knew that Earth wasn't the first world to colonize other planets. Remembering, Rick Mills felt mingled fascination and dread.

Fifty million years ago Mars and Planet X had been rivals. On Earth, the evidence of their final war must have been trampled under foot by the last of the dinosaurs, buried by volcanoes and rusted away by the damp climate. About the same had happened on Venus.

But on Earth's moon there still were gigantic bomb craters. And a few bright new weapons and engines of war, preserved perfectly by the vacuum. And two kinds of grotesque, dried-out corpses. In Mars' thin air and dryness, there still had been much weathering. But the fused-down, glassy remains of its cities, still slightly radioactive, lingered to show how the Martians had been wiped out.

The end of Planet X had been even more spectacular. Some colossal projectile must have drilled to its center to blow it apart, and form the thousands of fragments that were the asteroids. Drifting among them were the shattered cornices and columns of buildings, broken and cindered instruments and machines, art works, whatnot. So, two splendid technologies had perished with their creators.

Till on Earth science had risen again to challenge the primitive solar system. There were rich metals to be dug, new cities to be built for growing populations, adventures to be had, and knowledge to be gained and regained.

Mercury, too, had certainly been mixed up with that violent past. And now it hovered, a disturbing enigma, in both the immediate and the farther future. In only moments, now, that past would blend with the present. His—Rick Mills' present. Fane would be in it, too. With the brassy taste of worry before the nameless in his mouth, Rick realized how easy it might be to be unjustly suspicious. So he tried to fight off his tension, which most of his companions must share in some degree. He tried to substitute an adventurous eagerness.

Amid gusts of fire from its underjets the Sun Child thudded down at the old Martell campsite in Mercury's Twilight Belt which rings the planet between its hot and cold hemispheres. Here there is day and night of a sort. For Mercury, wobbling a little in its eccentric orbit, does not always keep exactly the same face turned sunward. In the Twilight Belt the sun sometimes rises slightly above the horizon, and then sinks back. Here there is no terrible heat or cold.

Everything was done now with swift precision. Like establishing a beachhead in some Earth-conflict of years ago. These five hundred men of the Survey Service, though civilians, functioned like a small army. They were the vanguard of research workers that must spearhead the occupation of yet another world. Bookish and academic they might seem, but they were trained for great ruggedness, too.

Working in space suits, they strung a security perimeter of electrified barbed wire around the ship. Breastworks were built and weapons were mounted against the unknown. Air tight tents to house testing instruments were set up and inflated. Everyone—Rick Mills, Lattimer, Turino, Finden, Schmidt, Horton, and the hundreds of others—toiled hard.

Then there was time to really look around. The dry rusty plain bore patches of low vegetation, with crinkly, silver-gray whorls. Lichen, it looked like. A sad remnant of life. In the all but airless sky stars blazed, even though a white-hot silver of the sun peeped above the brooding horizon, beyond which, for all one knew, great metal shapes might hide, waiting, preparing an ambush.

Nostrand, the leader of this expedition, held an aneroid barometer in his gloved hand. He was gray as iron, square-built of face and body, with widely separated teeth. He grinned, now, and spoke through his helmet radiophone:

"Funny. There's a wisp of air left. Small as it is, and with a gravity only one-fourth that of Earth, Mercury shouldn't have been able to hold down much of an atmosphere for more than a few thousand years. It should be as dead as our moon by now. A minor riddle, eh?"

Nostrand's tones fell, almost unnoticed, into a hollow stillness. Fane was standing near. He said nothing, but Rick Mills saw him grinning like a Cheshire cat.

Eyes continued to grope all around—at newness to them which was eons old. In the near distance was what seemed a highway. It ran east and west. One end vanished among the gloomy hills, at the fringe of the frigid hemisphere of eternal night. The other end reached straight across the plain toward where the top edge of the sun blazed supernally. In that direction the Twilight Belt turned gradually into unequalled desert.

Sunward along that highway, several ruined domes were visible, like scattered castles. They looked ancient Martian. Beyond them, out of sight, there must be others—buildings never made to offer shelter from the continuous, blazing radiation to which they were now exposed.

Also in sight on the highway was the wreck of a great turtle-like war engine, its triangular prow marking it as a probable product of Planet X. Doubtless, too, it had been an automatic, unmanned thing, capable of seeking out enemies by radar, and attacking, on its own, even without remote control. But if there was fear among those who saw it that the energy in it would be reawakened by their presence, this was dispelled as far as it was concerned. It lay on its side, torn out of shape, knocked out on the road those ages ago.

"Jeez!" some young guy muttered.

Then Nostrand spoke again, expressing most everyone's mood:

"Mercury was different when it rotated on its axis. Torrid, yes. But solar heat was nowhere continuous. Nor was darkness and cold. There were nights to cool off the heat of day. But the tidal drag of the too-near sun slowed the rotation. It must have stopped rather suddenly, as a wheel spinning against considerable friction stops. Then everything on Mercury changed, became extreme. It must have happened just about when the Martians and Xians were fighting each other. Maybe both sides held part of the planet at first...."

Nostrand's tone was musing and remote, hinting at pictures of ancient history. In his mind Rick Mills saw those dim pictures. His hide tingled. And his eyes combed the surrounding hills and plain warily. Was he looking for strange movement? This thought was tied up with the knowledge that, as on the moon, automatic machines could be perfectly preserved for millions of years here on weatherless Mercury, and that in some of them power might still be triggered into action by the disturbance of something penetrating a radio aura around them.

Rick spent some minutes with this scrutiny. By mood, nothing but a little dust and scant air molecules ever should stir on this tomblike planet. Once he may have imagined something small crawling on a hillside. But the second time, in a boulder-strewn gulch toward the dark hemisphere, and only a quarter-mile away, he could not be mistaken. A shape, hunched under a heavily loaded rucksack, was hurrying and dodging away. A man in space armor!

Rick gasped. He glanced around and then cursed. At once he had thought of Fane. Fane had been present moments ago. Now he was gone. Somehow Rick wished mightily that he had not lost sight of him for an instant.

"There goes Fane!" Rick yelled, pointing.

But while others took up the cry, Rick spied a piece of white notepaper at his feet. He picked it up and read:

"I'll drop this where you'll find it, Mills. So long. Thanks for the interest in me. It's flattering. I feel something is going to happen. I'm a lone wolf, unused to schoolbook greenhorns. I'm playing it single, and taking French leave. It's safer. I know you're supposed to go with a bunch into the dark hemisphere. Maybe I'll see you—if you live. Fane...."

Others read the note over Rick's shoulders. And other voices expressed some of Rick's scattered thoughts.

"Damn Fane! Something screwy about him. I always knew...."

"Sure! What's he trying to pull? What does he know about Mercury that he never told? Running out on us, now, huh? Six months he spent here once. Bet he did kill Martell and Jacobs! What is he after now? And what has he found out about the war machines that must be here?..."

"Easy, guys. No wolf-pack talk...."

"Easy—hell! If he didn't know his way around he'd never be wandering off like that on foot! His running off means no good...."

Then someone raised a long-range blaster. But before it could be fired at the dodging and elusive Fane, Nostrand struck the weapon down. The runaway had already reached the darkward foothills.

"It's no use trying to stop him now," Nostrand said.

"Fane—do you hear me?" Rick called, his helmet radiophone giving his voice the needed range. "Tell me, what's the pitch?"

Rick heard Fane's derisive and harsh laugh. "I told you, didn't I, smart boy Mills?" he taunted. "Or are you all stupid?"

The laugh and the words revealed more of Fane's nature to Rick than he'd ever seen before. The ego, the vanity, flaunted now because of some hidden advantage. Doubtless it salved an inferiority. Rick would have liked to like Fane. But now that big lanky man, for all his show of competence, was like a poisonous child.

Rick felt an amused smirk coming out on his own face in spite of his sense of the presence of masked danger. "Somebody has got the idea that he's super, Fane," he chuckled. "I wonder how that old, tiresome thing happened to you. Maybe you had a bitter, frustrated youth. Kids beat you up, hunh? So now you're the bigshot who makes monkeys out of everybody. Well, go play your marbles...."

Final response was only another harsh laugh.

For secrecy, Rick now cut off his radio, and established a sound-channel for his voice by grasping Nostrand's shoulder.

"We've got to follow him, Chief. See what he's up to," he said.

Nostrand nodded, and beckoned Schmidt, who was supposed to lead the pre-planned party into the dark hemisphere, to come closer. Nostrand spoke softly, with his phone also shut off:

"Of course. Things will proceed about as we intended. With the primary purpose of scientific exploration. But we'll cut the parties to ten men each to risk less personnel. One party with specially shielded space suits and tractors will invade the sunward hemisphere, while you folks will go the other way."

Within an hour, under Schmidt's able command, Rick and his other companions were moving along the highway toward the shadowy eastern hills, with two tractors fitted with pressurized cabins. Rick and two other men, Lattimer and Finden, rode atop the lead vehicle as lookouts.

Rick thought of how flexible a Survey Service guy had to be. Here their intended work was to learn about Mercury—to dig, even, into its crust, searching out its mineral wealth and learning its history, even back far beyond the rivalry of the Martians and Xians. A steaming, fast-spinning little world, it must have been once. And of course its now dubious value to modern civilization and economics must be judged.

But now another duty was added—something of criminal detection! There was suspicion without proof. Doubt that might be groundless, almost. Or that might point to a deadly unknown.

What must be Fane's tracks in the dust, were visible in one place for about a mile, along the hard-surfaced road. But then they vanished among the rocks. And what sense was there to try to hunt him out of the hills? Schmidt gave no such order. And Rick realized fully, then, that it was not so important to find Fane himself, but to learn what fabulous mystery it was that had made him hurry into this wilderness alone. Something tremendous must be at stake.

Miles were covered swiftly at first, making the sliver of sun sink from view to the rear. But one pale wing of the solar corona—a reminder, here, of the final sunset so long ago—still projected above the horizon, providing ghostly illumination. There was little talk, but Rick Mills felt as if he was invading some immense and haunted cellar, covering half a planet.

For young Finden to photograph, there were domed structures, vast buildings that might have been factories, huge slag heaps from mines, even the still standing trunks of trees, that had been perhaps developed from Martian stock. Thicker and thicker layers of frost and frozen air were over everything. And scattered along the road were the scars and wreckage of violence. Here, wood had been blackened by fire. Here, dug in the ground, had been a fortified strong point and supply-dump, full of toppled cylinders. Here there were dried-out, blackened corpses. The Martians, their many tentacles stiffened to the consistency of old wood, looked like charred tree-stumps. The Xians, with but four boneless limbs, were like deflated sacks of old leather.

There were great tanklike machines, of both Martian and Xian origin, blasted, and grotesquely toppled into ditches. There were metal forms, vaguely human and similarly torn. Here was all the evidence of battle and of Martian retreat. Mile by mile they must have been driven back toward some fortress deep in the now dark hemisphere.

And what comments were there to make now, about all this archaic fury that had gone silent and moveless those eons past? In momentary contact with their space suits, Rick Mills heard Finden's "Jeez!" and Lattimer's monosyllabic and awed curses. Fane had said something about a push-button war put into deep freeze.

"That's about the size of it," Rick said once to his companions. "Everything is in deep-freeze—almost absolute zero, and a vacuum, besides. No method of preservation could be much better."

It was as if here on the dark hemisphere, time had stopped with the ending of the passing days that measured it. Nowhere else in the solar system could the remains of that old conflict be better kept. And nowhere else were they more profuse.

It was hard not to think, now, that it was unwise to have come here so rashly. Rick had the feeling of having plunged too far into enemy territory where his bunch could be ambushed. For those war machines were not all smashed, certainly. Time meant nothing to them here. And the mystery of their function was half known from others like them on other worlds. There was always the chance that some of them would respond to the stimulus of detected movement around them. They were known to have intricate electronic relay systems inside them, almost brains.

"Keep your necks swivelling and your eyes peeled," Schmidt told his watchers on the tractor top, in a brief helmet phone message from inside the cabin.

"Don't worry, we will, Chief!" Lattimer growled back.

Overhead blazed the same constellations of stars known on Earth. Venus was glorious among them. Earth was dimmer—farther off. And it was the brilliance of that space-like star curtain that limned the first ugly moving silhouette. One of the man-like monsters was on the road ahead, its arms raised. Its great jutting thumbs of metal might have been the sort of things that had punctured the helmets of Martell and Jacobs. Perhaps this colossus had awakened on its own, as has been suggested. On the other hand, it might have been commanded by remote control, operating through radio impulses, of which the static-like whispers, barely noticeable in Rick's phones, might be the evidence.

To signal, Rick pounded on the roof of the tractor's cabin. And the men below fired their main blaster at once. The dazing blue flash of neutrons tore the metal giant apart with a spattering of incandescence. But then something fired back. There were two concussions and a blinding glare. Rick felt himself hurtling.

When he scrambled out of a deep snow-like drift, both tractors were blossoming white-hot vapors from their insides. In their cabins, no one could still survive, Schmidt, or any of the others. The lump was hard in Rick's throat, and the blur was thick and angry in his mind. He scrambled along the ditch, keeping down, firing at little shapes that scurried on the road. They were oval, half a foot long, like tortoises, but much faster. He'd seen their like at the Survey Service School brought from Earth's moon. Deadly little robots from X. They scuttled for cover. No use trying to dig them out. They were as elusive as rats. And they could fire atomic pellets.

Two more Earth-made blasters had been in action.

"We're still with you, Rick!" Finden risked saying by phone.

"Yeah, all I got out of it was some bruised ribs," Lattimer who was older, joined in, hiding a wince of pain.

While they were taping up a weak spot in Lattimer's armor, something spitting blue, like a rocket, arced overhead, and Rick was sure he heard a derisive chuckle in his phones. Fane.

"Damn him!" Lattimer snarled. "At the very least Fane would know how to use some of these machines after six months here. He'd know how to travel fast...."

Again, against the possibility of their conversation being overheard they were speaking directly by contact-transmitted sound.

"Keep down and tune in on camp," Rick said. "We can listen, anyway."

They heard strange noises. And then Nostrand's voice saying: "... We're under attack. A dozen war-robots. Parties afield please don't answer if there is danger of giving away your positions by radio-direction finder.... Ship already disabled...."

"It must be Fane doing it," young Finden snarled.

"Maybe. Not necessarily," Lattimer answered. "The question is, what do we do? Try to get back to camp on foot?"

Rick was younger and less experienced than the middle aged Lattimer but he felt the force of leadership coming over him. Most of it, perhaps, was fury, bringing the drive out in him—and bringing out an idea.

"We'd be of small use in camp," he said, "even if we could get there. Come on—crawl!..."

Rick had spied another Martian corpse, half-buried in a blanket of frozen air and frost a little way down the ditch. They reached it, and Rick ripped open the thin, rubberlike integument that had served its kind as space armor. Among its weird equipment Rick found a pouch held close to its hardened flesh. He drew out a parchment.

"Should have thought of this before," he growled. "In war they carried maps—Martians and Xians alike. Now let's see. What looks important on the dark hemisphere? Something that a guy like Fane would go for. If that's the way it is...."

The three men huddled together, squinting at the stiffened parchment in the dim light of the solar corona. Dark lines showed highways passing between jagged markings that must be mountain ranges. Rick coordinated what he knew of Mercury from astronomical photographs taken at the great observatory on the moon, with what he saw on the map, and thus found out where he and his companions were.

His attention was drawn inevitably to a great golden circle on the parchment. All roads led to it.

"No matter how you stack it, that must be the place we want to reach," Rick said. "But it's four thousand miles away."

"I see there's a tunnel, too," Lattimer joined in. "That heavy red line. I know Martian maps. It's for a kind of jet-train. Am I cockeyed to think that some cars might still work?... If we could get to a tunnel entrance. But it's fifty miles at the nearest. Some walk!"

"We're stranded in a white hell, with a good chance of being knocked off before we die from more natural causes," Finden said. "So we've got to think boldly. How about finding something like what Fane seemed to be using? Then we could rocket to that golden circle place."

"Yeah—'finding'," Rick retorted. "Then there's the question of our being able to fly it in a hurry. Uh-uh—the tunnel's a long shot, too, but a better bet. If we can locate a large, flat sheet of metal, we can bend up one end for a prow and use our blasters for reaction-propulsion to improvise a toboggan that will ski over the frozen air and frost."

They crept further along the ditch to get away from the deadly little ovoids that must still lurk near. Then they arose and ran. There was a dazzling blast from behind them, and they ran faster, maybe a mile or more, stumbling through deep drifts of white.

They came to more Xian wreckage. Hurriedly they searched, as some vague bulk prowled, far off to their left. But at last they found and shaped what they wanted. They crouched on the sheet of metal, and fired continuous streams of protons rearward. Soon their arms, braced against the thrust of incandescent fire, ached furiously.

The weapons were hot in their hands. But under the rocket-like kick of the blasters they made speed even though their makeshift toboggan, unguided by runners, careened crazily. The hour it took to cover fifty miles seemed an age.

Rick thought of Anne Munson, his girl, at the Survey Service School on Mars. But such sweet ruminations had no place here. He pushed them aside angrily. He wondered if Mercury would ever be worth anything, anymore. Mines it had, yes, but with one hemisphere frozen like this, and the other a furnace, would it ever be worth the trouble to build the insulated camps that would be needed to work those mines? Even the completely airless asteroids were less forbidding. And out there, in those fragments of a world, the metal-rich core of a planet was exposed for easy exploitation.

Dull fury took hold of Rick. At Fane. But more at the past, here. Wasted violence, buried in drifts of frozen atmosphere. Wasted energy. Why couldn't those beings have done better?

Near the end of the journey the toboggan hit a granite outcropping, that projected an inch above the layer of white, which was deeper here, farther inside the dark hemisphere. Rick and his companions were hurled cartwheeling into the drifts. It was minutes before they were conscious enough to move again.

Only Lattimer's pistol was not yet quite burnt out. So their crude vehicle was now useless. They had to continue toward the tunnel on foot.

"Somewhere around here," Rick muttered at last. "By the map, there should be an entrance. Don't know where we're going but we've got to hurry."

Looming dark and shattered under the stars was a tower. The three men struggled toward it. A shape was following them again.

Somehow they got inside the tower. Drifted atmosphere gave way under their feet. They were sliding down a kind of chute. It felt like the end of things. But in a minute they slid into an underground chamber. They wandered for a while amid Martian apparatus. They could still recognize transmutation equipment, though its vats and grids were cast in an un-Earthly form. The walls themselves glowed softly.

The injured Lattimer was the most exhausted but he still showed interest in things.

"The silicon in rock has an atomic structure not so far from that of oxygen and nitrogen, hasn't it?" he mused. "It could be redesigned a little. And the waste protons and electrons from the process could be used to make hydrogen for water. Besides, there's a lot of oxygen in mineral oxides. And water of crystallization, locked up, but ready made.... Water and air from rock! Earthmen can do that, too. Here the Martians must have done it all the time, replenishing the air and water constantly, and building up the supply. And when Mercury stopped rotating it just froze up here on the dark hemisphere, where, in solid form, it couldn't leak away into space anymore. It was just kept forever. So that much is explained. The Martians must have had a lot of these factories."

"Yeah, sure," young Finden growled. "Let's skip that, now. We've got to find the tunnel vehicles."

"We'll find them," Rick promised with a drunken sort of confidence. "And they should work if they aren't smashed. Preservation is perfect."

They moved as in a dream. But Rick was right. They descended a ramp. The frost of air around them was unmarked by footprints other than their own. They crept into a projectile-like car on a track, and fastened the door. The marvelous simplification of controls was evidence of an advanced technology. Was it so strange after all that when Rick pressed the throttle gingerly, a blast of atomic flame burst from the stern of the car, setting it in motion after so long?

Speed mounted. Colliding with anything in that tunnel would have brought the men unknowing death. But now the throttle was limp and unresponsive. So what was there to do but rely anxiously on probable automatic guiding devices? In minutes the car covered four thousand miles, and then stopped by itself with a soft, innocuous jolt.

Finden undogged the portal of the projectile by working levers not made for human hands. Again the glowing walls gave light. Boots made grating sounds. So there was air, too. Gaseous, not frozen.

Again they wandered through passages and rooms. Here was a great underground fortress and supply depot. Metal crates and boxes were stacked high. There were hugely buttressed walls, some of them ruptured and repaired. Martian and Xian corpses, relics of a last battle, lay dried out and blackened on the floor.

At last the men came to a long vaulted hall. Near them was the breech of a colossal tube, ten yards in diameter. Beyond it was another and another, a whole bank of them, fifty in a row, slanting slightly upward and disappearing into the metal wall.

The men sensed it at once—in this colossal setup must be what they had come to see. Here was the mysterious center of things.

They might have spoken of this aloud. But in this age-old place they were warned to silence. And it wasn't all intuition and wariness. For along the center of that hall, the dust was almost obliterated by human bootprints.

Stepping very lightly, Rick and his companions hid behind a metal column where a mummified Martian sprawled on the pavement amid heaps of parchment. Nearby was an Xian corpse.

Then they heard a voice. A whisper, almost. It came to their ears directly as sound, penetrating easily the insulating texture of their oxygen helmets:

"Give back a world.... Me...."

It was a man's gloating mutter to himself. A vain man's promise to his ego, which the frustrations and competition of life had made swollen, like a cancer.

Then they saw his blurred shadow on the wall. Thin, hunched over, working at something. Fane all right. He had arrived here ahead of them, by rocket vehicle. No chance could be taken, questioning him. That could be done when and if he was overpowered.

Rick Mills raced around the column and leaped. But the scrape of his space-boots was a small warning. Fane was almost able to meet him with the muzzle of a blaster. But Rick, hurtling into him with his shoulder, grabbed his wrist, and the weapon skittered across the floor. Yet though his face-window was open, Fane wore a space armor, too. It protected him from the onslaught. Besides, he was not near exhaustion. And his thin muscles were like wire cables. Moreover, he fought as if for all he had ever hoped for. Some terrific prize. He was like a silent maniac.

Even so, Rick almost pinned him down. Lattimer recovered the blaster. Finden was leaping. But Fane touched controls on a square box at his belt. A strange old box.

In obvious response, an Xian colossus of metal dashed forward from a far corner, its gleaming thumbs poised. Rick, dodging to one side, was forced to loosen his hold a little. Fane tore free.

Lattimer used the blaster. With a dazing glare its neutron stream cut the legs from the robot. The latter clanked to the floor.

"You found a remote control device, Fane," Rick accused. "The war robots are largely automatic, but you are directing them. Why?"

Fane made no denial. His face was a grimace of fury. He lunged behind another pillar.

"Get him before he really brings hell down on us!" Rick yelled.

Lattimer blazed away. Finden, who still had his original blaster, did likewise, discharging the weapon's last energy.

Incandescent chunks were torn from the walls and columns. Rick, Finden, and Lattimer ran after Fane but he managed always to keep some obstacle between them and himself. Twice, metal giants lunged at his pursuers and were cut down.

One victory the three loyal Survey Service men had. They drove Fane from that hall, with its row of the breech-ends of great tubes. Had he been able to stay a minute longer, calling more ancient battle forces to his aid, they would have been killed without further delay.

But there was defeat, too, in his escape from the hall. Considering what forces he must wield outside that was far from good.

Rick and his companions chased Fane up a spiral ramp, where the horny tendrils of Martians must once have scurried, and where, at the last, Xians must have fought them. Up and up the spiral went—it was hard to say how far. At last it seemed to be ascending inside a tower, for there were windows glazed with some clear substance. But beyond these panes, and close against them, there was nothing but whiteness. The tower was all but buried.

The climb ended in a round chamber fitted with an airlock. But when the men reached the latter, Fane had already passed through it to the outside.

Rick rubbed the rime of frozen atmosphere from a window, and they all peered out at a level waste, pale under the stars. Here at the center of the dark hemisphere, the deposit of congealed oxygen and nitrogen and water was so deep that it seemed even to have buried the mountains utterly. Perhaps the tower itself was on a mountain top. Even so, only its cupola projected above the desolation.

That and a row of gigantic pipe ends slanting upward from the super-frigid drifts. Their maws yawned black in the still bleakness.

For a moment the men almost forgot Fane, as they wondered what it was that they looked upon.

"Space ship launching tubes?" Finden suggested.

"I'm thinking of something else," Lattimer answered, his voice hollow and awed, yet somehow less tired.

"So am I," Rick put in. "I'm thinking of the breech-ends of these same tubes down below. And of an ordinary Fourth-of-July pinwheel made to spin by the tangential reaction of the gases of old fashioned gunpowder. And of what that screwball, Fane, muttered to himself. 'Give back a world.' Yeah. What was it that killed Mercury as a reasonably habitable planet?"

"I see what you mean," Finden growled. "Mercury stopped rotating. But about the rest you're absolutely nuts."

"Are we?" Lattimer challenged. "Does making a world rotate again, seem too big a job for a bank of atomic jets the size of these aimed just above the horizon? Those old Martians could have done it. And maybe our people could, too, allowing years of work and vast expenditure."

At that moment Rick Mills understood Frank Fane as never before.

"So this is supposed to be Fane's glory," Finden mused hoarsely, his eyes wide. "To give a ruined world back to civilization. Restore it. Not bad for an unknown pug-ugly even if the bug in his head says he has to kill everybody around and blame it on old war machines running amok by themselves so that there will be no division of triumph; so that, with all of us dopes dead, he'll look even bigger."

Lattimer's lips twisted. They were about to utter curses. But then, beyond the window, there was a dazzling flare of light. The men didn't ask what kind of missile had been launched against them. That they fairly tumbled down the spiral was all that saved their lives.

The terrible roar of sound itself seemed enough to kill. Automatic portals clanged above them to shut off the outrush of air and the influx of vaporized metal and radioactivity.

"We've got to block all entrances to the jet room!" Rick shrieked. "And we've got to see that there are no tin soldiers running around loose. Then...." Rick's voice trailed away.

With the blaster that had been Fane's, Lattimer brought down tunnel-roofs, barricading himself and his companions in the hall where the bases of the tubes were, behind tons of wreckage. It might help.

"Fane will try to dig us out, but now it should take a little time, I hope," Rick said. "We're buried deep in rock and snow and congealed atmosphere. And he probably hasn't enough war engines assembled around here to really try to blast through to us."

"So what do we do?" Finden demanded.

"Look around to see what we can do," Lattimer shot back at him.

They went down the row of great jet-tubes. To Rick's and Lattimer's trained eyes basic principles of function of these jets were not too hard to trace out. Regardless of what monsters on what world invented a thing, natural law remained the same. And so the shaping of metal and the directing of forces in any device had to remain the same everywhere.

"The setup isn't quite finished," Rick said. "Certain breech details aren't hooked together yet. But you can see where they go. Say, Fane must have spent most of his first six months on Mercury here in this vault trying to put what was left to do in order! A lot of these final touches must be his. He thought he could complete everything alone."

The evidence was clear. Empty food containers of Earthly origin were scattered about the floor. There were tools from the same source. And boxes of parts, made so long ago on Mars, were fairly free of dust, showing that they had been opened and their contents fastened into place quite recently in the gigantic assembly. And in one corner of this chamber a small Terran tent had been set up.

Fane had been working on something here when these three men had first found him. So now they went to see just what it was. They found a spread parchment on a work bench. It was blueprint stuff. Red lines traced the structure of the tube breeches. There were the fuel ducts in which an air blast fed the dust of uranium, and the exciter grids needed for firing. And there was the hookup of cables and bus-bars, needed to bind the whole bank of jets into a unit.

On the work bench there was even a book of advanced engineering brought from Earth. It lay open to a page on space ship motors.

Rick Mills saw more of the twisted soul of a man in the presence of that volume. "Poor Fane," he growled with bitter sarcasm. "Always making cracks about being bookish. Yet he found that he didn't have quite the knowledge to finish the assembly when he came here with Martell. He had to go home, study, get books."

"Given time, we can do what he can do," Finden said. "The still missing parts must be here somewhere."

"The Martians were close to completing the job themselves," Lattimer mused. "The Xians might have done it, too. I wonder just how it happened that Mercury was not reclaimed."

"Failure was also near," Rick said. "You can see that the Xians broke in through the underground fortifications with their robots. Meanwhile, on the hills outside, the snow of air was falling after the cold which followed the last sunset. There was a fight in these chambers at close quarters. The Xians had wanted to seize the setup intact, so they must have tried hard not to damage the main machinery here. But when they won, they lost. Maybe the news came that X was blown to pieces by Martian atomic science. Panic took hold, I'll bet. They fled Mercury, perhaps hardly believing that home was gone."

Rick's voice had become almost a harsh whisper. A savage bitterness smoldered in him. Around him, in the disorder of this chamber, and in the mummies of the two kinds of beings who had died, he saw how violence had blocked a great public work of peaceful constructiveness, and for fifty million years had robbed Mercury of a better destiny. For all of those ages it might have been a living, useful world instead of a half frozen, half sun-blasted tomb.

And was the same misfortune going to be repeated now because Fane was a childish damn fool?

From far above there came a thudding vibration. Fane was beginning his attack and Rick was by no means sure that his companions and he could finish the job in time. Fury in him mounted against the self-centered Fane and his inferiority.

"I'll raise the power in my helmet radio and try to contact camp!" Finden said. A moment later he was busy at it:

"CQ—CQ—CQ.... Calling Survey Camp. Finden speaking. Do you hear me? Fane is responsible for all of our troubles. The attack of the war machines. It is all because he has found a Martian jet-system to make Mercury rotate again. He wants to use it for personal glory. Do you hear me? Fane is guilty."

A sudden realization gripped Rick. He grabbed Finden's shoulders. "Stop!" he snapped. "Stop sending such a message! Don't you see? If Fane overheard...."

Both Finden and Lattimer stared at Rick.

"What difference does it make who sets Mercury spinning and makes it a useful, habitable world again as long as it's done?" Rick growled. "But if Fane felt that his goose was cooked, he'd wreck the whole works."

Rick gave his own helmet radio full power, and then spoke:

"Fane! I'm calling to you. This is Mills. We've seen what you found. We understand your purpose. It's your discovery, all yours. Come on, make peace. We'll help you put the stuff together."

No one knew how much will it took for Rick to be so unreasonably reasonable.

There was a minute's pause. Then a choked growl of rage. Fane's heavy breathing was audible before his hissing words: "You've talked too much already, smart guys! Tune in on camp and see!"

Rick and the others did so, and heard Nostrand's voice:

"Calling Finden. Your message received. Can you explain further? Camp still under attack."

They switched back to Fane, heard him snarl: "By now Nostrand will have relayed Finden's blabbing to Earth. Any investigation will be much too close. But if I'm finished, so are you. And Nostrand and all the others. Yeah, like Martell and Jacobs. And these jets. I'm playing for keeps, smart guys! If I can't use them, nobody's going to. You'll reach hell before I do."

Young Finden's eyes looked haunted. "Damn me!" he said. "If I'd only kept still."

"Forget it," Rick snapped. "You probably did as right as anybody could. Even if we had patched things up with Fane he probably would have found a way to finish us in the end."

"So let's get to work," Lattimer said briskly.

They examined the parchment plans. They tore through Martian crates and boxes searching for the proper parts. They used tools made for tentacles instead of hands. They toiled like demons. A dream not begun in human minds gripped them. It was only a hope, now, for they were sure that they did not have enough time. Give back a world. Give Mercury a day and night. Spread out the terrible sunlight and darkness. Balance the two to temper each other. Let the frozen air turn to warm wind, and the snow and frost melt. Let the fierce sunlight be filtered by clouds and atmosphere. Let vegetation grow again in tropic lushness. Let the mines be reopened.

And if it was possible, too, let the attack on the camp be lifted, and those still alive there, survive. There was even a wish among these three men that they themselves might not be destroyed.

Again Rick Mills had to shove the thought of Anne Munson almost angrily from his mind. It was a mere frivolity, useless and aching in these grim circumstances. A futile wistfulness, worse than the rest.

Time passed. One by one the tasks were finished. Now the men had a Martian generator going, a queer, flat device to produce electric power and to free neutrons from beryllium. Exciter neutrons for those great jet tubes.

Could it be believed that at last they had won nineteen hours of toil in their race to finish the job here, before Fane managed to kill them? They had fed huge quantities of familiar powder of uranium into the fuel blowers. They had set cables and grids into place. And still they continued to line things up, getting ready. During all this time there was only ominous, intermittent thudding, as from far away.

"Fane's gathering his robot forces," Finden said anxiously. "And now he can at least tear at the vents of the tubes, up above."

"I hope it won't matter," Rick answered.

They couldn't search out and understand everything that was here. The instruments that might have warned, or the weapons that might have defended them. But optimism came at last. Though it wavered some when they heard a faint grinding sound which seemed deep beyond the walls, but came closer. They hurried to hook up the last cable.

The thing that exploded must have been a mole-torpedo that drilled through rock and steel as fast as a man can walk. The walls of this vault did not break fully even under the Titanic force that hit them from outside. They bulged inward. A great section of the roof came down. Two of those huge jets were smashed. The whole chamber seemed to swing like a pendulum. A cable snapped in a flash of electric fire that consumed it.

Rick Mills hardly knew where he was now. He was too stunned. Lattimer was moveless beside him on the floor. Finden crawled on his elbows. Blood dribbled from his mouth. Rick had closed the main switch but the great apparatus here was not functioning. Maybe he dreamed it, but Rick was sure he heard Fane's bitter laugh.

"Just a few minutes more, Mills," he said. "Smart boy! We're all terribly smart, aren't we? We of the Survey Service. Sleep without dreams, Mills! Eternal sleep for fools like you and me!"

This was like the last act with the Martians and Xians. Almost a repetition. These were tortured seconds on which hung the future of Mercury as a Terran colony. Or was that already and badly decided? Must frozen silence and blazing heat continue, here? How many centuries must pass before Terrans would attempt to do for Mercury what the Martians had attempted? Or would they do so, ever? Silence. Silence and death would close in. Fane's robots were certainly aiming more mole-torpedoes.

It must not happen like that. Not again. Out of this thought in Rick's mind, an idea was squeezed. It challenged fate. It gave him the muscle power to arise. He staggered forward and grasped in his metal hands the fire-spitting end of the broken cable. The lining of the gloves was an insulation. He propped himself up with his steel-shod boot on the terminal that the cable was meant to reach. Heat oozed around him as the metal skin of his space suit took the cable's place as an electrical conductor.

Hell broke loose. Rick Mills and his companions felt a thunderous vibration, as of a million space ships blasting off, as all but two of those giant jet-tubes roared into life. Rick had propped himself well. Even when consciousness left him he maintained the electrical contact. Other mole-torpedoes, exploding, shook the chamber and bulged its walls. But the constructive fury that had started there, went on. It wasn't till half an hour later that those great tubes burned out.

No one ever saw the terrible blast of incandescence that they threw into space, like the jet of an old fashioned, Fourth-of-July pinwheel. Not even Fane, out there somewhere in the cold wilderness. Before he could glimpse what was happening, the glare charred his eyeballs. Then it charred him inside his space suit. Then a sea of slush engulfed him and his robots. A slush of liquid air and snow. Steam rose high and scattered to blank out the stars with an awful wind.

Five hours later the sun that had set here fifty million years ago, rose again. But the melting went on under the veil of fog. And across the furnace desert of Mercury, darkened now at last, rivers roared, hissing. Volcanoes blazed, for how can you cause a world to spin again, without poking up its internal fires with the strain?

But at last the fury of rebirth quieted. And down a murky river days later, a still dazed Rick Mills and his battered companions, paddled a crude metal boat to meet another party from the main camp. The air was thin and steamy, but rich in oxygen, and good to breathe. They had removed their space suit helmets.

Rick took out the picture of Anne Munson. He read the legend scrawled under her pert smile:

"Find us a world, Rick!"

"You thought you were pulling my leg, Miss Munson," Rick said solemnly. "But you'll be on Mercury, helping build things up, before you know it. Bet we'll even have a house...."

Young Finden's chuckle, and the twinkle in Lattimer's eyes, constituted another kind of leg-pull.