Those striations he thought he had seen on the ice, radiating inward from the rim wall, were actually ruts, he saw now, worn into water ice as hard as granite by the passage of countless feet, over countless years. All those journeys, he thought, shuddering, out to that great heaped-up pile of mummies. Year after year, generation after generation.

Dower hefted a weapon. “This is our way in. Form up.”

Abil stood at the head of his unit. Briefly he surveyed their faces. There were ten of them, all friends — even Denh. They would support him now to their deaths. But his stripes were only provisional, and he knew that if he fouled up they would chew jockey to replace him for the next drop, wherever and whenever it was.

That wasn’t going to happen. He grinned tightly. “Reds, forward.” They formed into two rows, with Abil at the head.

They trotted along the line of the path in the ice, keeping to either side of the rut, heading steadily toward the central mountain. The going turned out to be treacherous. Even away from the main paths the ice was worn slick by the passage of human feet. There were a few stumbles, and every so often there was a silent burst of vapor as somebody stepped into an oxygen puddle. Every time one of his unit took a pratfall Abil called a halt to run fresh equipment checks.

After about a mile Dower paused. The rut had led them to a crater in the ice, maybe ten yards across — no, Abil saw, the edges of this shallow pit were too sharp for that, its circular form too regular, and the base of the pit was smooth, gunmetal gray. Dower pressed her finger to the surface, and read Virtuals that danced before her Eyes. “Metal,” she said. She beckoned to Abil. “Corporal. Find a way in.”

He stepped gingerly onto the metal surface. It was slick, and littered with bits of loose frost, but it was easier than walking on the ice. He sensed hollowness beneath his feet, though, a great volume, and he trod lightly, for fear of making a noise. He knelt down, pressed his palm to the metal surface, and waited. Where his knee touched the metal he could feel its cold, clawing at him through the diamond pattern of heating filaments in his skinsuit. It took a few seconds for results from his suit’s sensors to be displayed, in hovering Virtuals before his face.

He was rewarded with a sketchy three-dimensional cross section. The metal plate was a couple of yards thick, and much of it was solid, fused on a base of rock. But it contained a hollow chamber, an upright cylinder. Probably some kind of low-tech backup system. The covering for the hollow was no more than a couple of yards away.

He walked that way and knelt again. His fingers, scraping over the sheer surface, quickly found a loose panel. By pressing on one side of it, he made it flip up. Beneath that was a simple handle, T-shaped. He grasped this, tugged. A lid rose up, attached by mechanical hinges.

Abil peered into the pit, using his suit lights. The pit was a little deeper than he was tall. He saw a wheel in there, a wheel set on a kind of spindle. Its purpose was obvious.

Dower came to stand beside him. She grunted. “Well done, Corporal. Okay, let’s take a minute. Check your kit again.” The troopers, working in pairs, complied.

Dower pointed at the mountain. “You were right — uh, Denh. The mountain’s tectonic, not impact- created. We’re standing over a midocean ridge: a place where the crust is cracking open, and stuff from within wells up to form new ocean floor. And where that happens, you get mountains heaping up, like this. On this planet it’s still happening. The loss of the sun destroyed the surface and the air, but it made no difference to what’s going on down deep. All along this ridge you will have vents, like valves, where the heat and the minerals from within the planet come bubbling up. And that heat will keep little pockets of water liquid, even now. And where there’s liquid water—”

“There’s life.” That mumble came from a number of voices. It was a slogan from biology classes taught to five-year-olds, all across the Expansion.

“And that is the ecosystem that will have survived this planet’s ejection from its solar system: something like bacteria colonies, or tube worms perhaps — probably anaerobic, living off the minerals and the heat that seeps out of the cracks in the ground. Radioactivity will keep the planet’s core warm long after that lost sun itself has gone cold. Strange irony — life on this world will probably actually last longer than if it had stayed in orbit around its sun …”

Abil piped up: “Tell us about the warren, sir.”

She began to sketch with one finger in the loose ice. “The warren is a rough toroid dug into the ice, encircling that central peak. In places it’s nearly a mile deep. It’s not a simple structure; it’s a mess of interconnected chambers and corridors. We suspect the birthing chambers are the deepest, the closest to the mountain rock itself; that’s the usual arrangement.

“Now here—” She slashed at her diagram, drawing diagonal lines that reached up from the torus and down to the face of the mountain. “Runs. Access chutes. Some of them vertical, probably the oldest,

fitted with lifting equipment; the more recent ones will have stairs and ladders. You can see these runs provide access to the surface, for the disposal of the dead, foraging missions for oxygen, perhaps other resources. These lower tunnels reach down to the face of the mountain, to the pockets of liquid water and the life-forms down there. With suitable processing the colonists will be able to live off the native organic compounds.” She looked up. “You need to know that it’s common for colonies of this type to reprocess as much of their raw material as possible.” She let that hang in the silence.

Denh said queasily, “You mean, people ? But we saw the corpses in that great ring.”

Dower shrugged. “In these wild warrens patterns vary … Just remember two things. First, across the Galaxy we are at war. Our alien enemy is pitiless, and cares nothing for your moral qualms, or even your nausea, Denh. We need warm bodies to be thrown into the war, and that’s why we’re here. We’re a press gang, nothing more. And second — remember that whatever you see down there, however strange it seems to you, these are human beings. Not like you — a different sort — but human nevertheless. So there’s nothing to fear.”

“Yes, sir,” came the ritual chorus.

“All right. Abil—”

Denh pushed herself forward. “Let me, Captain.” She jumped into the pit and rubbed her hands, pretending to spit on the palms, to the soft laughter of her mates. “Clockwise, you think?” She turned the wheel.

The ground shuddered under Abil’s feet. The great lid of metal and rock slid back, disappearing under the ice. Denh yelped, and jumped out of her hole.

The run was a broad, slanting tunnel cut into the ice. Crude steps had been etched into its lower surface, four, five, six parallel staircases. There was no light but the stars, and the spots of their skinsuits.

Eight of the ten teams would enter the run, leaving two on watch on the surface. Dower waved two units forward to take the lead. Abil’s red team was one of them.

Abil led the way into the hole. He clambered easily down the stairs, wary, descending into deeper darkness. His hands were empty; though the weapons of his team bristled behind him, he felt naked.

Abil had descended maybe two hundred yards into the hole when suddenly the ice under his feet shook again. The lid was closing over the hole, like a great eyelid, shutting out the stars. He heard hurried, gasping breaths, the sounds of panic rising in his troopers. He tried to control his own breathing. “Red team, take it easy,” he said. “Remember your briefing. We expected this.”

“The corporal’s right,” growled Dower, somewhere above him. “This is just an air lock. Just wait, now.”