Part 3

They'd followed the huge trail that had been visible on their first landing in the polar regions. The great, two-yard-across pads of the monster had made a clear trail for ten miles from the point of their discovery. At the end of the trail there was a great gap in a cliff of frozen sand. The Thing seemed to have devoured tons of ice-impacted stuff. Then it had gone back into the swirling sandy wastes. It carried away with it cubic yards--perhaps twenty or thirty tons--of water-filled frozen sand.

But reason insisted that there could be no animal life on a planet without plants, and no plants on a desert which was the scene of daily typhoons, hourly hurricanes, and with no water anywhere upon it save at the poles. And there was no vegetation there. A monster with dozens of six-foot feet, and able to consume tons of wetted sand for moisture, would need vast quantities of food for energy alone. And it was unthinkable that food was to be found in the strangling depths of perpetual sandstorms.

"There's another thing," Stan added. "With power to spare I could fuse sand into something like a solid. Make a house, maybe, and chairs to sit on, instead of having to wear our space suits all the time. Maybe we could even heat the inside of a house!"

Esther smiled at him.

"Darling," she said wryly, "you've no idea how glad I'd be of a solid floor to walk on instead of sand, and a chair to sit on, even if we didn't have a roof!"

They had been, in effect, in the position of earth-castaways marooned on a sand-cay which had not even seashells on it or fish around it. There was literally nothing they could do but talk.

"And," she added, "if we could make a tub to take a bath in--"

She brightened at the thought. Stan hadn't told her of his own reasons for having no hope. There was no point in causing her despair in advance.

"We'll see what we see," he said. "Climb aboard."

The space skid was barely five feet long. It had a steering bar and a thick body which contained its power-storage unit and drive. And there was the seat which one straddled, and the strap to hold its passenger. Two people riding it in bulky space suits was much like riding double on a bicycle, but Stan would not leave Esther alone. Not since they'd seen that horrifying trail!

They rose vertically and headed south in what was almost a rocket's trajectory. Stan, quite automatically, had noted the time of sunrise at the incredible structure beside which he'd landed. Later, he'd noted as automatically the length of the planet's day. So to find his original landing place he had only to follow the dawn line across the planet's surface, with due regard for the time consumed in traveling.

They were still two hundred miles out in space when he sighted the grid. He slanted down to it. It was just emerging from the deep black shadow of night. He swooped to a landing on one of the hundred-foot slabs of hinged metal three hundred feet above ground. It was clear of sand. It had obviously been dumped.

Esther stared about her, amazed.

"But--people made this, Stan!" she insisted. "If we can get in touch with them--"

"You sit over there," said Stan. He pointed to an intersection of the criss-crossing girders. "It takes power to travel near a planet. My power bank is half drained already. I'd better fill it up again."

He got out his cutting-torch. He turned it upon a motor-housing. The plastic coating frizzled and smoked. It peeled away. Metal flared white-hot and melted.

There was a monstrous creaking. All the plates in a square mile turned. Swiftly. Only a desperate leap saved Stan from a drop to the desert thirty stories below.

The great slabs pointed their edges to the sky. Stan waited. Esther said startledly;

"That was on purpose, Stan!"

"Hardly," said Stan. "They'll turn back in a minute."

But they did not turn back. They stayed tilted toward the dawning sky.

"You may be right, at that," said Stan. "We'll see. Try another place."

Five minutes later they landed on a second huge slab of black metal, miles away. Without a word, Stan ensconced Esther on the small platform formed by crossing girders. He took out the torch again. The tiny, blue-white flame. Smoke at its first touch. Metal flowed.

With a vast cachinnation of squeakings, a mile-square section shifted like the first....

"Something," said Stan grimly, "doesn't want us to have power. Maybe they can stop us, and maybe not."

The swelling which was the motor-housing was just within reach from the immovable girder crossing on which Esther waited. Stan reached out now. The torch burned with a quiet fierce flame. A great section of metal fell away, exposing a motor exactly like the one he'd first examined--slabs of allotropic graphite and all. He thrust in and cut the cables. He reached in with the charging clips--

There was a crackling report in the space skid's body. Smoke came out.

* * * * *

Stan examined the damage with grimly set features.

"Blew another fuse," he told Esther. "We're licked. When I took power the first time, I ruined a motor. It's been found out. So the plates turned, today, to--scare me away, perhaps, as soon as I cut into another. When I didn't scare and severed the cables, high-voltage current was shot into them to kill me or ruin whatever I was using the power for. Whether there's life here or not, there's intelligence--and a very unpleasant kind, too!"

He re-fused the skid, scowling.

"No attempt to communicate with us!" he said savagely. "They'd know somebody civilized cut into that motor-housing! They'd know it was an emergency! You'd think--"

He stopped. A faint, faint humming sound became audible. It seemed to come from nowhere in particular--or from everywhere. But it was not the formless humming of a rising wind. This sound was a humming punctuated by hurried, rhythmic clankings. It was oddly like the sound of cars traveling over an old-fashioned railway--one with unwelded rail joints. Then Esther jerked her head about.

"Stan! Look there!"

Something hurtled toward them in the gray dawn light. It was a machine. Even in the first instant of amazement, Stan could see what it was and what it was designed to do. It was a huge, bulbous platform above stiltlike legs. At the bottoms of the legs were wheels. The wheels ran on the cross-girders as on a railroad track, and the body of the thing was upraised enough to ride well above the sidewise-tilted slabs. There were other wheels to be lowered for travel on the girders which supported the slabs.

It was not a flying device, but a rolling one. It could travel in either of two directions at right angles to each other, and had been designed to run only on the great grid which ran beyond the horizon. It was undoubtedly a maintaining machine, designed to reach any spot where trouble developed, for the making of repairs, and it was of such weight that even the typhoonlike winds of a normal day on this world could not lift it from its place.

It came hurtling toward them at terrific speed. It would roll irresistibly over anything on the girders which were its tracks.

"Get on!" snapped Stan. "Quick!"

Esther moved as swiftly as she could, but space suits are clumsy things. The little skid shot skyward only part of a second before the colossus ran furiously over the place where they had been. A hundred feet beyond, it braked and came to a seemingly enraged stop. It stood still as if watching the hovering, tiny skid with its two passengers.

"It looks disappointed," said Stan dourly. "I wonder if it wants to chase us?"

He sent the skid darting away. They landed. In seconds the vibration caused by the huge machine's motion began and grew loud. They saw it race into view. As it appeared, instantly a deafening clamor began. Slabs in all directions rose to their vertical position, so that the two humans could not dodge from one row of girders to another. And then with a roar and a rush the thing plunged toward them once more.

Again the skid took off. Again the huge machine overran the spot where they had been, then stopped short as if baffled. Stan sent his odd craft off at an angle. Instantly the gigantic thing was in motion, moving in lightning speed in one direction, stopping short to move on a new course at right angles to the first, and so progressing in zigzag but very swift pursuit.

"'Won't you land so I can crush you?' said the monster to us two," said Stan dryly. "They won't let us have any more power, and we haven't any more to waste. But still--"

He listened to his suit-radio, twisting the tuning dials as he sent the skid up in a spiral.

"I'm wondering," he observed, "if they're trying to tell us something by radio. And meanwhile I'd like a more comprehensive view of this damned checkerboard!"

A faint, faint, wavering whine came into the headphones.

"There's something," he commented "Not a main communication wave, though. A stray harmonic--and of a power beam, I think. They must use plenty short waves!"

But he was searching the deadly monotony of the grid below him as he spoke. Suddenly, he pointed. All the area below them to the horizon was filled with geometric shapes of grids and squares. But one space was different from the rest. Four squares were thrown into one, there. And as the skid dived for a nearer view, that one square was seen to be a deep, hollow shaft going down toward the very vitals of this world. As Stan looked, though, it filled swiftly with something rising from its depths. The lifting thing was a platform, and things moved about on it.

"That's that!" said Stan hardly.

He shot the skid away in level flight at topmost speed, with the great rolling machine following helplessly and ragingly on its zigzag course below.

The horizon was dark, now, with the coming night. As Stan lifted for the rocketlike trajectory that would take him back to the polar regions, the white sun sank fiercely. There was a narrow space on which the rays smote so slantingly that the least inequality of level was marked by shadow. Gigantic sand dunes were outlined there. But beyond, where the winds began, there was only featureless swirling dust.

Stan was very silent all the way back. Only, once, he said calmly, "Our power units will soak up a pretty big charge in a short time. We packed away some power before the fuse blew."

There was no comment for Esther to make. There was life on the planet. It was life which knew of their existence and presence--and had tried to kill them for the theft of some few megawatts of power. It would not be easy to make terms with the life which held other life so cheaply.

With the planet's only source of power now guarded, matters looked less bright than before. But after they had reached the icecap, and when they slanted down out of the airlessness to the spot which was their home because their seeds had been planted there--as they dived down for a landing, their real situation appeared.

There was a colossal object with many pairs of legs moving back and forth over the little space where their food plants sprouted. In days, those plants would have yielded food. They wouldn't yield food now.

Their garden was being trampled to nothingness by a multilegged machine of a size comparable to the other machine which had chased them on the grid. It was fifty feet high from ground to top, and had a round, tanklike body all of twenty feet in diameter. Round projections at one end looked like eyes. It moved on multiple legs which trampled in orderly confusion. It stamped the growing plants to pulped green stuff in the polar sand. It went over and over and over the place where the food necessary for the humans' survival had promised to grow. It stamped and stamped: It destroyed all hope of food. And it destroyed all hope.

Because, as Stan drove the skid down to see the machine more clearly, it stopped in its stamping. It swung about to face him, with a curiously unmachinelike ferocity. As Stan veered, it turned also. When he sped on over it and beyond, it wheeled and came galloping with surprising speed after him.

Then they saw another machine. Two more. Three. They saw dark specks here and there in the polar wastes, every one a machine like the one which had tramped their food supply out of existence. And every one changed course to parallel and approach the skid's line of travel. If they landed, the machines would close in.

There was only so much power. The skid could not stay indefinitely aloft. And anywhere that they landed--

* * * * *

But they did land. They had to. It was a thousand miles away, on the dark side of the planet, in a waste of sand which looked frozen in the starlight. The instant the skid touched ground, Stan made a warning gesture and reached over to turn off Esther's suit-radio. He opened his own face-plate and almost gasped at the chill of the midnight air. With no clouds or water vapor to hinder it, the heat stored up by day was radiated out to the awful chill of interstellar space at a rate which brought below zero temperatures within hours of sundown. At the winter pole of the planet, the air itself must come close to turning liquid from the cold. But here, and now, Stan nodded in his helmet as Esther opened her face-plate.

"No radio," he told her. "They'll hardly be able to find us in several million square miles if we don't use radio. But now you get some sleep. We're going to have a busy time, presently!"

Esther hesitated, and said desperately, "But--who are they? What are they? Why do they want to kill us?"

"They're the local citizens," said Stan. "I was wrong, there are inhabitants. I've no more idea what they may be like than you have. But I suspect they want to kill us simply because we're strangers."

"But how could an intelligent race develop on a planet like this?" demanded Esther unbelievingly. "How'd they stay alive while they were developing?"

Stan shrugged his shoulders.

"Once you admit that a thing is so," he said dryly, "you can figure out how it happened. This sun is a dwarf white star. That means that once upon a time it exploded. It flared out into a nova. Maybe there were other planets nearer to it than this, and they volatilized when their sun blew up. Everything on this planet, certainly, was killed, and for a long, long time after it was surely uninhabitable by any standard. There's a dwarf star in the Crab Nebula which will melt iron four light-hours away--land that was a nova twelve hundred years ago. It must have been bad on this planet for a long time indeed.

"I'm guessing that when the first explosion came the inner planets turned to gas and this one had all its seas and forests and all its atmosphere simply blasted away to nothingness. Everything living on its surface was killed. Even bacteria in the soil turned to steam and went off into space. That would account for the absolute absence of life here now."

"But--" said Esther.

"But," said Stan, "the people--call them people--who lived here were civilized even then. They knew what was coming. If they hadn't interstellar drive, flight would do them no good. They'd have nowhere to go. So maybe they stayed. Underground. Maybe they dug themselves caves and galleries five--ten--twenty miles down. Maybe some of those galleries collapsed when the blow-up came, but some of the people survived. They'd stayed underground for centuries. They'd have to! It might be fifty thousand years they stayed underground, while Khor Alpha blazed less and less fiercely, and they waited until they could come up again.

"There was no air for a while up here. They had to fight to keep alive, down in the planet's vitals. They made a new civilization, surrounded by rock, with no more thought of stars. They'd be hard put to it for power, too. They couldn't well use combustion, with a limited air supply. They probably learned to transform heat to power direct. You can take power--electricity--and make heat. Why not the other way about? For maybe fifty thousand years, and maybe more, they had to live without even thinking of the surface of their world. But as the dwarf star cooled off, they needed its heat again."

He stopped. He seemed to listen intently. But there was no sound in the icy night. There were only bright, unwinking stars and an infinity of sand--and cold.

"So they dug up to the surface again," he went on. "Air had come back, molecule by molecule from empty space, drawn by the same gravitation that once had kept it from flying away. And the fused-solid rock of the surface, baked by day and frozen by night, had cracked and broken down to powder. When air came again and winds blew, it was sand. The whole planet was desert. The people couldn't live on the surface again. They probably didn't want to. But they needed power. So they built that monster grid they're so jealous of."

"You mean," Esther demanded incredulously, "that's a generator?"

"A transformer," corrected Stan. "Solar heat to electricity. Back on Earth the sun pours better than a kilowatt of energy on every square yard of Earth's surface in the tropics--over three million kilowatts to the square mile. This checkerboard arrangement is at least a hundred and fifty by two hundred miles. The power's greater here, but, on Earth, that would mean ninety thousand million kilowatts. More than a hundred thousand million horsepower--more than the whole Earth uses even now!

"If those big slabs convert solar radiation into power--and I charged up the skid from one of them--there's a reason for the checkerboard, and there's a reason for dumping the sand--it would hinder gathering power--and there's a reason for getting upset when somebody started to meddle with it. And they're upset! They'll have the conservation of moisture down to a fine point, down below, but they made those leggy machines to haul more water, from the poles. When they set them all to hunting us, they're very much disturbed! But luckily they'd never have worked out anything to fly with underground and they're not likely to have done so since--considering the storms and all."

There was a short silence. Then Esther said slowly, "It's--very plausible, Stan. I believe it. And they'd have no idea of space travel, so they'd have no idea of other intelligent races, and actually they'd never think of castaways. They wouldn't understand, and they'd try to kill us to study the problem we presented. That's their idea, no doubt. And they've all the resources of a civilization that's old and scientific. They'll apply them all to get us--and they won't even think of listening to us! Stan! What can we do?"

Stan said amusedly, there in the still, frigid night of an unnamed planet, "Why--we'll do plenty! We're barbarians by comparison with them, Esther, and barbarians have equipment civilized men forget. All savages have spears, but a civilized man doesn't even always carry a pocketknife. If we can find the _Erebus_, we can probably defy this whole planet--until they put their minds to developing weapons. But right now you go to sleep. I'll watch."

Esther looked at him dubiously. Five days of sandstorms should have buried the little yacht irrecoverably.

"If it's findable," she said. Then she added wistfully, "But it would be nice to be on the _Erebus_ again. It would feel so good to walk around without a space suit! And--" she added firmly, "after all, Stan, we are engaged! And if you think I like trying to figure out some way of getting kissed through an opened face-plate--"

Stan said gruffly, "Go to sleep!"

* * * * *

He paced up and down and up and down. They were remarkably unlike castaways in the space tale magazines. In those works of fiction, the hero is always remarkably ingenious. He contrives shelters from native growths on however alien a planet he and the heroine may have been marooned; he is full of useful odd bits of information which enable him to surprise her with unexpected luxuries, and he is inspired when it comes to signaling devices. But in five days on this planet, Stan had been able to make no use of any natural growth because there weren't any. He'd found no small luxuries for Esther because there was literally nothing about but sand. And there was strikingly little use in a fund of odd bits of information when there was only desert to apply it to--desert and sandstorms.

What he'd just told Esther was a guess; the best guess he could make, and a plausible one, but still a guess. The only new bit of information he'd picked up so far was the way the local inhabitants made electric motors. And he had to bet his and Esther's life on that!

He watched the chrono. And a good half hour before night would strike the checkerboard grid, he was verifying what few preparations he could make. A little later he waked Esther. And just about twenty minutes before the sunset line would reach the grid, they soared upward to seek it. If Stan's plan didn't work, they'd die. He was going to gamble their lives and the last morsel of power the skid's power unit contained, on information gained in two peeps at slab-motors on the grid, and the inference that all motors on this planet would be made on the same principle. Of course, as a subsidiary gamble, he had also to bet that he in an unarmed and wrecked space yacht could defy a civilization that had lived since before Khor Alpha was a dwarf star.

They soared out of atmosphere on a trajectory that saved power but was weirdly unlike any normal way of traveling from one spot on a planet's surface to another. Beneath them lay the vast expanse of the desert, all dense, velvety black except for one blindingly bright area at its western rim. That bright area widened as they neared it, overtaking the day. Suddenly the rectangular edges of the grid shed appeared, breaking the sharp edge of dusk.

The _Erebus_ had grounded about fifty miles northward from the planet's solitary structure. Stan turned on his suit-radio and listened intently. There was no possible landmark. The dunes changed hourly during the day and on no two days were ever the same. He skimmed the settling sand clouds of the dusk belt. Presently he was sure he had overshot his mark.

He circled. He circled again. He made a great logarithmic spiral out from the point he considered most likely. The power meter showed the drain. He searched in the night, with no possible landmark. Sweat came out on his face.

Then he heard a tiny click. Sweat ran down his face. He worked desperately to localize the signal Esther had set to working in the yacht before she left it. When at last he landed and was sure the _Erebus_ was under the starlit sand about him, he looked at the power gauge and tensed his lips. He pressed his space helmet close to Esther's, until it touched. He spoke, and his voice carried by metallic conduction without the use of radio.

"We might make it if we try now. But we're going to need a lot of power at best. I'm going to gamble the local yokels can't trace a skid drive and wait for morning, to harness the whirlwinds to do our digging for us."

Her voice came faintly back to him by the same means of communication.

"All right, Stan."

She couldn't guess his intentions, of course. They were probably insane. He said urgently:

"Listen! The yacht's buried directly under us. Maybe ten feet, maybe fifty, maybe Heaven knows how deep! There's a bare chance that if we get to it we can do something, with what I know now about the machines in use here. It's the only chance I know, and it's not a good one. It's only fair to tell you--"

"I'll try anything," said her voice in his helmet, "with you."

He swallowed. Then he stayed awake and desperately alert, his suit-microphones at their highest pitch of sensitivity, during the long and deadly monotonous hours of the night.