Because of that insistence she had lain in the snow with a shattered leg for a day and a night before a search party had discovered her.

The drone Jase started to give her the details of the flight of the nameless ship from its mother-craft, of its interception and self-destruction. Fal had turned her head, though, and was only half listening. Her eyes and mind were on the distant, snowy slopes, where she hoped she would be climbing again in a few days" time, once these stupid bones in her leg had thoroughly healed.

The mountains were beautiful. There were other mountains on the up slope side of the lodge terrace, reaching into the clear blue sky, but they were tame stuff indeed compared to those sharp, rearing peaks across the plain. She knew that was why they had put her in this lodge; they hoped she would climb those nearer mountains rather than take the trouble to hop into a flyer and head over the plain. It was a silly idea, though; they had to let her see the mountains, or she wouldn't be herself, and as long as she could see them she just had to climb them. Idiots.

On a planet, she thought, You wouldn't be able to see them so well. You wouldn't be able to see the lower foothills, the way the mountains rise from the plain just so.

The lodge, the terrace, the mountains and the plain were on an Orbital. Humans had built this place, or at least built the machines that built the machines that… Well, you could go on and on. The Plate of the Orbital was almost perfectly flat; in fact, vertically it was slightly concave, but as the internal diameter of the completed Orbital — properly formed only once all the individual Plates had been joined up and the last dividing wall was removed — would measure over three million kilometres, the curvature was a great deal less than on the convex surface of any human-habitable globe. So from Fal's raised vantage point she could see right to the base of the distant mountains. Fal thought it must be very strange to live on a planet and have to look over a curve; so that, for example, you would see the top of a seaship appear over the horizon before the rest of it.

She was suddenly aware that she was thinking about planets because of something Jase had just said. She turned round and looked earnestly at the dark grey machine, playing back her short-term memory to recall exactly what it had just said.

"This Mind went underneath the planet in hyperspace?" she said. "Then warped inside?"

"That was what it said it was trying to do when it sent the coded message in its destruct pattern. As the planet is still there it must have succeeded. Had it failed, at least half a per cent of its mass would have reacted with the planet's own material as though it was antimatter."

"I see." Fal scratched at one cheek with a finger. "I thought that wasn't supposed to be possible?" Her voice contained the question. She looked at Jase.

"What?" it said.

"Doing…" She scowled at not being immediately understood and waved one hand impatiently."… Doing what it did. Going under something so big in hyperspace and then bouncing over. I was told even we couldn't do that."

"So was the Mind in question, but it was desperate. The General War Council itself decided that we should try to duplicate the feat, using a similar Mind and a spare planet."

"What happened?" Fal asked, grinning at the idea of a «spare» planet.

"No Mind would even consider the idea; far too dangerous. Even the eligible ones on the War Council demurred."

Fal laughed, gazing up at the red and white flowers curled round the trelliswork overhead. Jase, which deep down was a hopeless romantic, thought her laughter sounded like the tinkling of mountain streams, and always recorded her laughs for itself, even when they were snorts or guffaws, even when she was being rude and it was a dirty laugh. Jase knew a machine, even a sentient one, could not die of shame, but it also knew that it would do just that if Fal ever guessed any of this. Fal stopped laughing. She said:

"What does this thing actually look like? I mean you never see them by themselves, they're always in something… a ship or whatever. And how did it — what did it use to warp with?"

"Externally," Jase said in its usual, calm, measured tones, "it is an ellipsoid. Fields up, it looks like a very small ship. It's about ten metres long and two and a half in diameter. Internally it's made up of millions of components, but the most important ones are the thinking and memory parts of the Mind proper; those are what make it so heavy because they're so dense. It weighs nearly fifteen thousand tonnes. It is fitted with its own power, of course, and several field generators, any of which could be pressed into service as emergency motors, and indeed are designed with this in mind. Only the outer envelope is constantly in real space, the rest — all the thinking parts, anyway — stay in hyperspace.

"Assuming, as we must, that the Mind did what it said it was going to do, there is only one possible way it could have accomplished the task, given that it does not have a warp motor or Displacer." Jase paused as Fal sat forward, her elbows on her knees, her hands clenched under her chin. It saw her shifting her weight on her backside and a tiny grimace appear fleetingly on her face. Jase decided she was getting uncomfortable on the hard stone bench, and ordered one of the lodge drones to bring some cushions. "The Mind does have an internal warping unit, but it is supposed to be used only to expand microscopic volumes of the memory so that there is more space around the sections of information — in the form of third-level elementary particle-spirals — which it wants to change. The normal volume limit on that warping unit is less than a cubic millimetre; somehow the ship Mind jury-rigged it so that it would encompass its entire body and let it appear within the planet's surface. A clear air space would be the logical place to go for, and the tunnels of the Command System seem an obvious choice; that is where it said it would head for."

"Right," Fal said, nodding. "OK. Now, what are — oh…"

A small drone carrying two large cushions appeared at her side. "Hmm, thanks," Fal said, levering herself up with one hand and placing one cushion beneath her, the other at her back. The small drone floated off to the lodge again. Fal settled herself. "Did you ask for these, Jase?" she asked.

"Not me," Jase lied, secretly pleased. "What were you going to ask?"

"These tunnels," Fal said, leaning forward more comfortably this time. "This Command System. What is it?"

"Briefly, it consists of a winding, paired loop of twenty-two-metre diameter tunnels buried five kilometres deep. The whole system is several hundred kilometres in length. The trains were designed to be the wartime mobile command centres of a state which once existed on the planet, when it was at the intermediate-sophisticated stage-three phase. State-of-the-art weaponry at the time was the fusion bomb, delivered by transplanetary guided rocket. The Command System was designed to-"

"Yes." Fal waved her hand quickly. "Protect, keep mobile so they couldn't be blown up. Right?"

"Yes."

"What sort of rock cover did they have?"

"Granite," Jase said.

"Batholithic?"

"Just a second," Jase said, consulting elsewhere. "Yes. Correct: a batholith."

"A batholith?" Fal said, eyebrows raised. "Just one?"

"Just one."

"This is a slightly low-G world? Thick crust?"

"Both."

"Uh-huh. So the Mind's inside these…" She looked along the terrace, not really seeing anything, but in her mind's eye looking down kilometres of dark tunnels (and thinking there might be some pretty impressive mountains above them: all that granite; low-G; good climbing territory). She looked at the machine again. "So what happened? It's a Planet of the Dead; did the natives eventually do it to themselves?"