Sanchez shook Jason awake. "Come on, Kid. We're going ice-side."
"What?" He wriggled out of his bag and kicked off to follow her down the corridor.
"Nobody's got any use for a couple of pilots today," she went on. "They're busy taking inventory of all the equipment around here. So, we're going down to Valhalla to have a look around."
"On Callisto?"
"More like in Callisto, but that's the general idea. You've never been on the surface of a planet, have you? Here, put this on."
They had arrived at a changing room next to the hangar and she had given him a suit of extraordinarily massive leathers.
"What is it?" he asked, strapping on the vest and leggings and a kind of harness.
"Body armour. Standard Security issue. There's a steel mesh and a reflective foil between the leather and the lining. Should stop most non-explosive bullets and some hand-lasers. I don't suppose you've ever fired a gun."
"No, the bow is my weapon. Do we have any super-bows here?"
"Fedorova will design one for you and get Davis to build it. Kill a deer from thirty miles away and broil you a venison steak by the time you get there. But for now, all we have is this." She pulled out a bulky pistol and showed him its operation. "This is the laser-sight. When you see the light flicker on whatever you want to kill, pull the trigger. These are explosive shells. For God's sake, don't shoot me. Come on."
She tapped open the Cheshire Cat's access lock and swung toward the pilot's couch.
"What happened to Dar and Rani?"
"They're in storage. We never did decide on a proper service, though we did have a damn fine wake. They've waited a hundred years; a few more days won't kill them."
Jason resisted pointing out the obvious fact that they were already dead. He strapped himself in beside her as she tapped switches on the instrument panel. A fluorescent jungle of holographic figures flashed into view about them.
"We don't need most of this crap." Sanchez tapped several switches a second time and the information was considerably reduced. "Hecate?"
"Yes, Sanchez."
"You won't be able to maintain contact when we're under the ice. Can you evaluate the Cat's data now?"
"You have an up-to-date map of Valhalla in the files. I have indicated the portion that is radiating most visibly in infra-red. If there are any inhabitants at all, they must be there. Be careful, Maria."
"I'm always careful," she laughed. The Cat's drivers roared into life and dropped to a purr. Jason heard the hiss and clank of disengagement and the ship drifted through the open space-doors.
Jason was thrust back into his couch as the drivers roared once more and the vessel seemed to plummet into the planet below. He was used to the Argo's launch, which floated through the dark from sailing ship to port and back again like a leaf on the surface of a pond. This was more like a rock falling out of the sky. Callisto spread out below like the Argo's sails, and just as Jason was certain they were going to plunge into the ice, there was a great cloud of billowing vapour beneath and they lighted like a butterfly.
The drivers' roar dropped to a murmur, and they sat motionless on a vast, cracked glacial plain, Jupiter peering at them over the distant peaks of a mountain range. There was a horizon--sharply drawn between ice and black sky--and there was weight pressing him to his couch. The world did not curve up overhead and back again; it curved down and out of sight. He was on the surface of a world, but it was the coldest, most lonely world he could imagine. Even in the bright, humming cabin, the loneliness seemed to creep into his bones.
Sanchez studied the three-dimensional map, tilting it one way and another with a joystick. She glanced out the port to orient herself and pushed forward a lever. There was a whir and a clunk and a hiss, and the main part of of the Cheshire Cat’s driver-system separated from behind them.
She thrust the lever away from her and they sped off across the ice. In a monitor, Jason could see steel runners sliding and tracks biting into the surface. In another monitor, he could see the bulk of the ship dwindling behind them, waiting forlornly on a tripod of landing gear. They skimmed over the scintillating ice with dazzling speed and Jason grinned with pleasure. The mountains thrust skyward before them, blotting out Jupiter's face, seemingly an impenetrable barrier. But suddenly there was a yawning cavern in a cliff-face and the Cat roared into it.
A few floodlights still burned. The Cat slowed to a crawl and nosed up to a hatch set in the icy wall before them. Sanchez tapped out a pattern and a thin arm thrust forward from the ship's bows, gripped a small wheel in its pincers, and rotated. The hatch door rose, the Cat trundled into a lock, and the hatch shut again behind them. There was a brief flurry of snow, and tiny rivulets of water ran across the port. Finally, there was a hiss as the atmosphere in the lock became dense enough to carry sound, a second hatch opened before them, and the Cat slipped through into fairyland.
The light from the ceiling-panels far above was dim and flickered madly, but Jason could soon see that they had entered one of a series of canal-side villages connected by now-frozen grottoes. The streets and parks and terraces were adrift in snow, dead trees stark against the white background. The houses and public buildings, the haloed streetlamps and ornate balconies and catwalks were encased in solid ice, or festooned with great icicles, or imprisoned behind the icy bars of translucent stalactites. The entire cavern glittered and twinkled and shimmered as the failing lamps flickered overhead, and the only sound was the fitful buzzing that they made.
The Cat crept through the village streets on snow-muffled treads. Front doors of shops were left open, windows were broken, furniture and clothing were scattered in the snowy streets. Sanchez stopped and observed the frozen corpses lying in heaps in the snowdrifts.
"There may be heat radiation, relatively speaking," she said, "but there's nothing alive here." She called up the map and watched it revolve, then waved it away and gunned the engines. The Cat trundled down a ramp, turned in its own length, and sped up a frozen canal. Icy tunnel walls flashed by, and they emerged into another cavern, slowed, and slid to a halt before an impressive public building. Stone pillars rose from snow-clad steps and the great carved beasts on either side wore winter coats of frost.
"Guard the ship," said Sanchez. "There may be some information in the library. Like where the population might have gone when they abandoned the city." She touched a button at her breast and Jason felt her clothing give off warmth as she un-strapped and opened the hatch. There was a blast of frigid air and he switched on the heater in his own suit, felt warm air rising over his face. Sanchez stomped down the ramp in her treaded boots, a little unsteadily in the gravity, and through the port Jason saw her leave footprints in the snow as she climbed the stairs to the library.
"Guard the ship?" Jason repeated. The open hatch beckoned to him. He un-strapped and struggled to his feet on rubbery legs, then made his way cautiously down the ramp. He stood, his boots gripping the ice, and gazed at the frozen desolation about him. "Guard the ship from what, I'd like to know."
The snow crunched beneath his feet as he walked, ducking under the ship's bow, into the centre of the street. The library stood proudly behind its pillars, but most of the other buildings had collapsed at least partially with the weight of accumulated frost.
Suddenly there was a noise--a kind of dull thud--that seemed unnaturally loud in the frozen silence. Jason crept closer to the ruins of a store and peered down into its black cellar; a portion of the sidewalk had collapsed with the front of the building. He thought he heard a muffled scraping sound from within, and he was debating whether to return to the ship, fetch Sanchez, or what, when a human figure bounded from the depths of the ruin and ran headlong into him.
Both went sprawling in the icy street with a cry of surprise. The other leaped to his feet and began to run, then stopped and whirled to face Jason. He spoke in a hoarse voice, as if he had not had occasion to speak in a very long time.
"You're human," he said.
"Yes," replied Jason, and they stared at each other.
The man was clad in armour not unlike Jason's, though it was torn and burned so that tarnished metal showed through the filthy leather in spots. He was missing one boot, his foot wrapped in foil of some sort and tied with wire. He wore a dented helmet and a patch on one eye, and he limped badly on his bandaged foot. Some of his fingers were missing, and what was visible of his face through the helmet was badly scarred and burned.
He seemed about to speak again when there was a great crash behind Jason and the stranger looked up. Before Jason could turn, a bolt of blue lightning flashed over his shoulder and straight into the stranger's chest. His body seemed to explode and went flying across the ice.
Jason whirled and saw a monstrous machine emerge from the ruin behind him. It moved on two legs in a grotesque parody of a human walk, but its legs were thick as pillars and when its great three-clawed foot came down on the ice, there was a sickening crunch and cracks spread out in all directions. It had four arms: two were more like tentacles, one of which was broken, and two ended in huge claws, one of which held a smouldering laser-weapon. The awful creature was twice Jason's height, and around its massive waist was a belt of human skulls.
Jason was frozen in shock and horror as it took one more crunching step and swivelled its huge head obscenely to stare at him.
"Human," it said, neither asking a question nor expressing surprise. Its voice was hollow and artificial. It took another step.
Jason pulled out his own weapon and levelled it at the creature. A tiny spot of red light trembled madly on the monster's chest. Jason tried to say something threatening, but all that came out was a croak.
The machine lifted its ponderous foot to take another step and Jason pulled the trigger. The weapon's recoil knocked him off his feet and the exploding shell blew the monster back into the ruins with a great crash and a minor snowslide.
"Human," it said, and began to rise.
Jason sat up and pulled the trigger again, and again, and again. There was a series of explosions whose echoes rolled back and forth in the cavern, and great chunks of metal flew in all directions. The ruin of the killing machine lay twitching and smoking in a steaming pool of boiling water, and Jason sat trembling on the ice, clicking the trigger of an empty gun.
"Jesus Christ!" came the voice of Sanchez. She pounded down the steps and raced into the street, her own weapon in her hand. She stood and surveyed the scene.
"I can't leave you alone for a minute, can I?"
"What?"
"I turn my back and you kill two robots."
"Two robots?" Jason turned to the fallen stranger and saw, for the first time, the wires and tubes protruding from its ruined chest.
"It's an android," said Sanchez. She examined the belt of skulls the killing machine wore. "And these are android heads."
"I thought they were..."
"I know what you thought, and I guess I don't blame you for blowing it away. Damn good shooting, too, incidentally." She kicked at the smouldering pieces. "We won’t get any information out of this one, or the other one either. Come on; we’d better tell Fedorova about this development." She turned and Jason followed her to the ship.
"Did you find anything in the library?"
"I’ve got a message tape in my pouch. I was right: the whole human population migrated, heading back to Earth. There hasn’t been anyone here for a century, which is why your friend there was so surprised to see you he couldn’t resist coming in for a closer look."
"I’m sorry now," Jason said. "If I’d just told him to stop, I guess he would have obeyed. But I’d just seen him kill what I thought was a man."
"Well, nobody’s going to blame you for reacting the way you did, but I wonder what possessed the thing to start hunting androids."
***
"Parts," said Fedorova.
"What?"
"I should have thought of it before. When the human population left, the first two laws ceased to have any meaning. There was no one to protect from harm, and no orders to obey, unless it was something like: 'Wait for us to return, and take care of yourselves,' which would only have reinforced the third law. 'Protect your own existence.' It doesn't say anything about protecting each other's existence, does it? So, when their parts began to wear out, the simplest thing to do was to take them by force from another robot."
"The law of the jungle," said Davis.
"Exactly. The big mining and industrial robots would have their strength and the weaker androids their intelligence and adaptability."
"Survival of the fittest," said Sanchez. "I suppose this thing carried around the heads of its victims for spare brain-parts. Its brains would certainly wear out faster than its limbs, which are pretty much indestructible in that model."
"Yes, and it could change programs that way," Fedorova added. "Adapt. Which robots of that type are not designed to do."
"That sounds like evolution," said Davis.
"That's right. But what's rather frightening about it is that such robots are usually just as incapable of harming an android as a human being, because of the outward similarity. This robot had overcome that inhibition. With the continual strengthening of the third law and weakening of the first, I wonder if some of them might not develop an indifference to human suffering in the interest of their own survival, becoming as callous as human beings themselves."
"Precisely our greatest fear, Professor."
There was a general intake of breath at the sound of the unfamiliar voice, coming over the station's comm system. Heads swivelled, and Sanchez' hand flew to her weapon.
"Who is that?" Davis demanded. "Where are you?"
"Sorry to eavesdrop like this, but the conversation was so fascinating. This is Mining Colony Delta, on its way to join you in Callisto orbit."
"Who are you? Human survivors?"
"No, I'm afraid not. This is an all-robot civilization. I'm the current leader, Fiver Niner, and I look forward to meeting you all. We have much to discuss."