"They've been here, I'm sure of it!" Barendts waved at the tunnel behind him. "Just a bit further."

"I'm with you." Michael couldn't read the marine's expression through his facemask. He knew Barendts was eager to prove that this abandoned sub-ice town held autotroph trash. He was as unhappy as Michael to be stranded on this halo world, so far from the action. He wanted to have something to show for their time here, if and when they succeeded in getting back to High Space.

The tunnel he was pointing to looked unstable, however. Large slabs of its wall bulged inward, become as malleable as wax from the pressure of all the ice above it. Long cracks ran up those swollen walls.

The bots seemed calm, though; Michael sighed again and swam after Barendts. "Just this last one," he said. "Then we go back, empty handed or no."

The autotrophs didn't exactly trade with their fanatical green skinned worshippers. They disposed of garbage by either dropping it into the deep ocean, or hiding it in any of thousands of abandoned tunnels that riddled the coast of the Northern Ocean. Humans had lived here for centuries, and boom towns had sprung up and vanished many times, some on the surface, some in the depths. The green men explored the caverns, and occasionally came out with treasures they could trade to the university for hard currency. Michael and Barendts had spied on them long enough to pick up their search habits, and then had begun looking themselves. Several times now, they had discovered lodes of autotroph technology, hidden deep in the collapsing grottoes where no sane human would normally venture.

A chain of madly swimming bots lit the ice tunnels ahead of Michael, so that even when Barendts went behind a wall, he could see the marine's moving green trail through the ice. He followed the bots around the corner, and found himself at the bottom of a shaft braced with corroded rails: the familiar shape of an old elevator shaft. This was a lucky find, it might give them access to levels of the settlement unreachable by other means.

Barendts's shout confirmed his hope. "It's the frickin' town hall!" His helmet lamp whipped back and forth at the top of the shaft, casting shadows and highlights down the walls. In moments Michael was beside him, gasping despite himself at the place they had come to.

Sometime in the distant past, settlers had carved out a large cavern here, maybe with a clean nuke. Michael's headlamps couldn't reach the end of it. Maybe it was a hundred meters across— maybe a thousand. All was darkness beyond the feeble fan of his light, but that glow was strong enough to pick out drowned buildings: He saw walls and the black maws of open doorways, windows.

"Supremely creepy," said Barendts. The marine sounded happy— as he always was when he had something to do.

They had been sharing an apartment now for four months. Ever since Rue Cassels stranded Michael here on Oculus, he had been trying to get back to the Rights Economy. (Well, she hadn't really stranded him, he knew; she was stuck here, too, at least for now.) Michael had been adrift for too long, and was almost grateful to her for forcing a decision upon him. He was no longer permitted to speak to her, or to Laurent Herat, and so he'd had to make some long-deferred decisions. He had decided to become a rebel again.

It was just a shame that there was no way he could act on that decision, trapped as he was in the halo worlds.

"Come on!" Barendts shot away into the submerged streets of the cavern settlement. Michael followed, trying to ignore the way this place reminded him of Dis.

Those dire kami seldom visited him these days. He felt he was, if not getting over that experience, at least slowly reaching an accommodation with it. Unfortunate, then, to have to swim past these empty facades and hear the kami whisper in the back of his mind, so strong, so sad.

"Heads up!" That was Barendts, his voice suddenly urgent. Suddenly, all the bots went dark, leaving Michael staring into the narrowed cone of light from his own headlamp— light that showed only grainy water, and the corner of a long-abandoned building.

Prudently, he tuned that light down to a vague glow, and switched on his goggles' light amplifiers. "What is it?" he radioed.

"Visitors," said Barendts curtly. It took Michael a few minutes to find the marine in the speckly gray shadowland of the now-dark town. Barendts was hovering behind a half-fallen wall that might once have defined someone's garden, back when the invisibly distant ceiling held sunlamps and there was air here instead of water. Barendts pointed over the wall as Michael slid next to him.

Lights wavered in the distance. Michael counted seven sources, about half a kilometer away. This cavern was indeed huge. From here, all he could see was diffuse greenish lozenges slowly moving around the abandoned buildings.

"I'll send a bot," said Barendts.

"No." Michael put a hand on the marine's shoulder. "I want to see this myself."

Barendts started to protest, but Michael ignored him, kicking strongly into the darkness beyond the wall. It made sense to send the bots ahead, but Michael had never been one to hide behind remotes— a trait he'd picked up from Herat, most likely. Better to do fieldwork yourself.

Anyway, he had not ceased to be a scientist by choice. Michael was still welcome at the university, but he couldn't work with Laurent Herat, because the professor had signed some kind of secrecy deal along with Rue Cassels. Whatever the secret was, it was paid for by turning their backs on the struggles of the people in the Rights Economy. Michael was surprised and hurt that Herat of all people should be willing to do that— the Cycler Compact might be a declining power, but its decline was slow and graceful. It didn't involve the deaths of millions.

Michael had petitioned the Compact to allow Barendts and himself to return to the R.E. It was absolutely critical that the rebels learn about the weapon Crisler hoped to find at Osiris and Apophis. Rue knew that, and she had the ear of the highest officials in the government.

The petition had been turned down, without explanation.

Every day that passed, Crisler drew closer to the Twins, and to escaping with the Chicxulub weapon. Frustration had drawn Michael back to the autotrophs as much as curiosity. Frustration drove him now as he closed in on the distant lights, for the university had refused to allow him to visit the green men again. Herat could; Michael was only partially mollified by the knowledge that even Herat had not been allowed to visit the autotrophs themselves.

He took a roundabout route, hiding behind the softening outlines of buildings, confident in his destination because the glow was constantly visible. Finally only one building separated him from whoever it was; he took a chance, and swam into the crumbling structure itself.

The walls were peeling, the floor covered in a layer of hazy mud. The feeling of desolation here was overwhelming, and he could feel his NeoShinto implant stirring, finding echoes of the kami of lost lives here. Michael ignored it, and made his way to a room at the front of the building.

The wall here had numerous holes in it. Light shone strongly through them, and he could hear a thrumming sound through the water now. Michael swam slowly over and put his goggles against one of the lower holes.

Not three meters away, a thing like a giant silver scarab was lowering boxes and canisters off its back, and arranging them carefully in the silt. There was no recognizable head to the thing, nor any sense organs he could see. But drifting around and above it were hundreds of tiny bright beads.

Michael recognized them: They were like the ones that had swarmed around him and Herat during their visit to the autotrophs four months ago. The swarm had spoken to them; it was an integral part of the autotrophs' artificial intelligence.