He made a resigned sort of gesture with his hands, putting them both down on the stone parapet, gazing out to the darkening sky. Beychae was silent.

He gave the old man a while longer to think, then looked round at the flat stone summit of the hill, at all the strange stone instruments. "An observatory, eh?"

"Yes," Beychae said after a moment's hesitation. He touched one of the stone plinths with one hand. "Believed to have been a burial site, four or five thousand years ago; then to have had some sort of astrological significance; later, they may have predicted eclipses with readings taken here. Finally, the Vrehids built this observatory to study the motions of the moons, planets and stars. There are water-clocks, sundials, sextants, planet-dials… partial orreries… there are crude seismographs here, too, or at least earthquake direction indicators."

"They have telescopes?"

"Very poor ones, and only for a decade or so before the Empire fell. The results they got from the telescopes caused a lot of problems; contradicted what they already knew, or thought they knew."

"That figures. What's this?" One of the plinths held a large, rusty metal bowl with a sharp central spindle.

"Compass, I think," Beychae said. "It works by fields," he smiled.

"And this? Looks like a tree stump." It was a huge, rough, very slightly fluted cylinder perhaps a metre in height, and twice that across. He tapped the edge. "Hmm; stone."

"Ah!" Tsoldrin said, joining him at the stone cylinder. "Well, if it's what I think it is… it was originally just a tree stump, of course…" He ran his hand over the stone surface, looked round the edge for something. "But it was petrified, long ago. Look though; you can still see the rings in the wood."

He leant closer, looking at the grey stone surface by the fading afternoon light. The growth rings of the long dead tree were indeed visible. He leant forward, taking off one of the suit gloves, and with his fingers stroked the surface of the stone. Some differential weathering of the wood-become-rock had made the rings tangible; his fingers felt the tiny ridges run beneath their surface like the fingerprint of some mighty stone god.

"So many years," he breathed, putting his hand back to the very sapling centre of the stump, and running his hand out again. Beychae said nothing.

Every year a complete ring, signature of bad year and good by the spacing, and every ring complete, sealed, hermetic. Every year like part of a sentence, every ring a shackle, chained and chaining to the past; every ring a wall, a prison. A sentence locked in the wood, now locked in stone, frozen twice, sentenced twice, once for an imaginable time, then for an unimaginable time. His finger ran over the ring walls, dry paper over ridged rock.

"This is just the cover," Beychae said from the other side. He was squatting down, looking for something on the side of the great stone stump. "There ought to be… ah. Here we are. Don't expect we'll be able to actually lift it, of course…"

"Cover?" he said, putting the glove back on and walking round to where Beychae was. "Cover for what?"

"A sort of puzzle the Imperial Astronomers played when the viewing was patchy," Beychae said. "There; see that handhold?"

"Just a second," he said. "Want to stand back a little?" Beychae stood back. "It's supposed to take four strong men, Zakalwe."

"This suit's more powerful than that, though balancing might be a little…" He found two hand-holds on the stone. "Suit command; strength normal max."

"You have to talk to the suit?" Beychae asked.

"Yeah," he said. He flexed, lifting one edge of the stone cover up; a tiny explosion of dust under the sole of one of the suit's boots announced a trapped pebble giving up the struggle. "This one you do; they have ones you just have to think about something, but…" he pulled on one edge of the cover, sticking one leg out to shift his centre of gravity as he did so."… but I just never liked the idea of that." He held the whole stone top of the petrified stump above his head, then walked awkwardly, to the noise of crunching, popping gravel under his feet, to another stone table; he lowered, shifted the stone cover sidways until it rested on the table, and returned; he made the mistake of clapping his hands together, and produced what sounded like a gunshot. "Oops," he grinned. "Suit command; strength off."

Revealed by the removal of the stone cap was a shallow cone. It seemed to have been carved from the petrified stump itself. Looking closer, he could see that it was ridged, tree ring by tree ring.

"Quite clever," he said, mildly disappointed.

"You're not looking at it properly, Cheradenine," Beychae told him. "Look closer."

He looked closer.

"I don't suppose you have anything very small and spherical, do you?" Beychae said, "Like a… ball-bearing."

"A ball-bearing?" he said, a pained expression on his face.

"You don't have such things?"

"I think you'll find in most societies ball-bearings don't last much beyond room-temperature superconductivity, let alone field technology. Unless you're into industrial archeology and trying to keep some ancient machine running. No, I don't have any ball…" he peered closer at the centre of the shallow rock cone. "Notches."

"Exactly." Beychae smiled.

He stood back, looking at the ridged cone as a whole. "It's a maze!"

Maze. There had been a maze in the garden. They outgrew it, became too familiar with it, eventually only used it when other children they didn't like came for the day to the great house; they could lose them in the maze for a few hours.

"Yes," Beychae nodded. "They would start out with small coloured beads or pebbles, and try to work their way to the rim." He looked closer. "They say there might have been a way to turn it into a game, by painting lines that divided each ring into segments; little wooden bridges and blocking pieces like walls could be used to facilitate one's own progress or prevent that of one's rivals." Beychae squinted closer in the fading light. "Hmm. Paint must have faded."

He looked down at the hundreds of tiny ridges on the surface of the shallow cone — like a model of a huge volcano, he thought — and smiled. He sighed, looked at the screen set into the wrist of the suit, tried the emergency signal button again. No reply.

"Trying to contact the Culture?"

"Mmm," he said, gazing again at the petrified maze.

"What will happen to you if Governance find us?" Beychae asked.

"Oh," he shrugged, walking back to the balustrade they had stood at earlier. "Probably not much. Not very likely they'll just blow my brains out; they'll want to question me. Should give the Culture plenty of time to get me out; either negotiated or just snapped away. Don't worry about me." He smiled at Beychae. "Tell them I took you by force. I'll say I stunned you and stuffed you into the capsule. So don't worry; they'll probably let you go straight back to your studies."

"Well," Beychae said, rejoining the other man at the balustrade. "My studies were a delicate construction, Zakalwe; they maintained my carefully developed disinterest. They may not be so easy to resume, after your… exuberantly violent interruption."

"Ah." He tried not to smile. He looked down at the trees, then at the suit gloves, as though checking all the fingers were there. "Yeah. Look, Tsoldrin… I'm sorry… I mean about your friend, Ms Shiol."

"As am I," Beychae said quietly. He smiled uncertainly. "I felt happy, Cheradenine. I hadn't felt like that for… well, long enough." They stood watching the sun sink behind the clouds. "You are certain she was one of theirs? I mean, absolutely?"

"Beyond any reasonable doubt, Tsoldrin." He thought he saw tears in the old man's eyes. He looked away. "Like I said; I'm sorry."

"I hope," Beychae said, "that is not the only way the old can be made happy… can be happy. Through deceit."