Tony's grandfather had purchased her fifty years ago, but she was much older than that although she claimed to have forgotten her original identity and the circumstances of her death and lamination, she said that she had been born on Earth and could remember what it was like before the Jackaroo had arrived in the aftermath of the Spasm, with their offer to help. And while she was an imperfect simulation running in the laminated architecture of her original brain, got up from bundles of reflexes, habits and memories, Tony never doubted that there was an actual person behind the hands and windows she used to interact with the world: astute, absent-minded, and somewhat remote, wryly amused by what she called the eternal theatre of human folly, and unswervingly loyal. She tutored the family's children, was involved with Orelolu's work on sleepy sickness, supervised research on introducing salmon into Skadi's icy ocean, increasing the efficiency of the kraken-oil refinery and improving the cultivation of pine trees and the quality of their timber. She had advised Tony about the deals he had made during his two years of freebooting, analysed artefacts he had sent back to Skadi, and expressed enthusiasm for the slime-planet adventure, whose success now hung on the fraying hope that the wizards would find something in the stromatolites' archival genetics that could be linked to sleepy sickness.

This was not the first time she had asked Tony to provide more processing space; like all laminated minds she tended to repeat herself, was locked in the deep grooves of old obsessions. He patiently explained that he had twice asked the council to grant the wizards access to the city net, and had twice been refused for the same reason. 'They want the work quarantined. They are worried that an eidolon will leak out. Or some kind of meme plague even worse than sleepy sickness.'

'Did you tell them about the firewall I devised?'

'They were not convinced. We must manage with what we have.'

'Unless we access the city net anyway.'

'We cannot do that without permission from the council.'

'I need only permission from a member of the family, Master Tony.'

Tony glanced across the work space to the kitchen area, where Lancelot Askia sprawled in a chair, watching something in a window. Hopefully one of his pornographic war fantasies, not a feed from a drone that Aunty Jael had failed to find and subvert.

He said, 'Have you talked to anyone else about this?'

'Of course not. They would not agree to it.'

'Neither can I. It would be sedition.'

'I agree that it would be a drastic measure,' Aunty Jael said. One of the stalked eyes that crowned the hand's stubby trunk was watching the wizards working below; the rest were aimed at Tony. 'But shutting down this research would be a bad mistake. The archival genetics are rich in unrealised potential. Since you cannot extend the time granted for this research, I feel that it is my duty to suggest ways of making the most of what you have.'

Tony thought for a moment, then said, 'Could you link me with my ship?'

He missed her more than he could say, was always aware of the silence in his head, of being trapped alone in his skull.

'I'm afraid not,' Aunty Jael said. 'I do not have access to that system.'

'Then think of something else. Think of a way of making our wizards do what they're actually supposed to be doing.'

The wizards had been working in Aunty Jael's laboratory for twenty-nine days now. Tony and Aunty Jael were supervising them; Junot Johnson sourced the materials and items of equipment they required; Lancelot Askia was a permanent reminder of Opeyemi's disapproval, skulking around, examining the wizards' notes and worksheets, asking awkward questions. Their new leader, Cho Wing-James, claimed that the work had already yielded some very interesting results. He and the other wizards had dissected the complex molecular machinery that replicated the archival genetic material, were developing a working model of the stromatolites' data-transmission system, and had disproved several theories about the mathematical systems of the Old Old Ones. The problem was that Cho Wing-James's ideas about what was interesting had very little overlap with Tony's, and none at all with the family's.

Cho Wing-James was the beanpole who had charged at Tony after the thermobaric bomb had been planted, an animated, untidy scarecrow with a ragged mop of hair, given to mumbling cryptic snatches of internal dialogue and smacking his forehead with the heel of his hand as if trying to dislodge a jammed gear train in the mechanism of some internal argument. He claimed that he was from Earth. From London, England. He'd come all the way out here, he said, because this was where the shit was at. The real shit, not Boxbuilder ruins or Ghostkeeper tombs, or even archival genetics containing secrets millions of years old. He believed that there were Elder Culture artefacts so wild and strange that people had not yet recognised them for what they were.

'The Jackaroo gave us wormholes and shuttles,' he said, 'and we understand those because, hey, shuttles are basically big old spaceships, and we already had crude spaceships when the Jackaroo made contact. And although we didn't know how to open wormholes, we had theories about them, so the idea that they allow near-instantaneous travel to every part of the Milky Way wasn't new or startling. It's the same with most Elder Culture tech. It's the kind of stuff we might have come up with, in time. But there are a few artefacts that are so weird we barely recognise them as artefacts, and can't begin to understand their function, and it's not much of a leap to believe that there's stuff we don't even recognise as technology. Stuff so advanced that it makes us look like insects walking through the interface of a qube. At best we might glimpse a bare flicker of light, but we'd have no way of knowing what it means.'

He could happily elaborate his ideas about hyper-evolved Elder Cultures for hours, said that it was quite possible that there were aliens far more advanced than the Jackaroo civilisations that could harness the entire energy output of stars, construct megastructures like Dyson spheres and stellar engines, manipulate space-time, and organise information flow across the galaxy or even the entire universe. These beings, Cho said, would be like gods. Incomprehensible, unknowable, unseeable.

'I don't mean that they look and behave so differently we think they're animals, or biochines, or like the trees you have here,' he said. 'If they are trees.'

'We call them trees,' Tony said. 'Because that's what they are.'

'Well, they look more like giant kelp to me, or big mops stuck in the ground and spray-painted unnatural shades of yellow and orange. This world, it's like it's always autumn. You know? The chill in the air, the colours of the vegetation. Or what passes for vegetation. But the angle of light, the verticality of it, is tropical. It's a weird combination. Anyway, the kelp-mop-tree-things, they could be an Elder Culture species, communing through what passes for their root systems, through chemicals they release into the air. Thinking really slow thoughts that take decades to complete. But mistaking them for trees when really they're sentient beings is only a category error. Trying to detect and understand a truly advanced civilisation would be a completely different order of difficulty. And that's what makes it so exciting,' Cho said.

He was not interested in the uses of knowledge; he was interested only in how it confirmed or changed his theories of how the world worked. A common failing in wizards, who dosed themselves with drugs that accentuated obsessive-compulsive traits, and infected themselves with memes and partial eidolons to help them intuit the workings of Elder Culture algorithms. Unlike Fred Firat, who'd struck Tony as a sturdily practical sort, Cho Wing-James treated the stromatolites' archival genetics as an intricate and fascinating puzzle rather than a library of ancient and potentially valuable secrets. He and his crew had squandered days studying some kind of Ghajar algorithm lodged in the magnetite arrays of the stromatolites; Cho had claimed that it might have been some kind of translation tool left over from an attempt by the Elder Culture to crack the archival genetics, but nothing had come of it.

At last, frustrated by his inability to persuade Cho to focus on finding something, anything, that could persuade the family council to extend its deadline, Tony took the wizard up to the clinic to show him what was at stake. It was Danilo Evangalista's idea, actually. After listening to Tony vent one day, the young singer had asked if Cho had ever seen the effects of sleepy sickness. It turned out that the wizard hadn't. It wasn't something that had ever interested him, he said.

Tony was astonished. 'Even though I hauled you and your friends out to the slime planet because Fred Firat claimed that the stromatolites would help us understand meme plagues?'

'Oh, I know that Fred believed that,' Cho said airily. 'But I was only ever interested in the actual science.'

'Sleepy sickness is an actual thing, too,' Tony said. 'It's time you realised that.'

Tony, Danilo and Cho Wing-James travelled out to the clinic the next day, flying north in a spinner helmed by Lancelot Askia a condition imposed by Opeyemi in return for permission to take the wizard on the little trip. Danilo pressed close to the transparent aluminium of the spinner's bubble, pointing out sights to Cho as the spinner rose above the close-packed roofs of the city and flew out over patchwork farms and pine plantations, and the orange and yellow native forest climbing the slopes of the foothills. Snowy mountain peaks were chalkily sketched against the blue horizon, the boundary between the northern edge of Skadi's habitable strip of land and the vast ice cap that stretched away towards the north pole.

Tony was charmed by Danilo's innocent delight in these vistas. The singer wore the white fur jacket that Tony had given him for this trip, his long legs encased in tight red jeans. When he looked around and asked if that was the clinic ahead, his smile turned Tony's heart.

'Yes,' he said. 'Yes, it is.'

'It's bigger than I thought it would be,' Danilo said.

The spinner was flying above a lake towards rugged cliffs divided by the white ribbon of a waterfall. The heaped geodesic domes of the clinic straddled the swift river that fed the waterfall, glinting in cold sunlight and caught between steep slopes of yellow forest.

'When I had a work placement here, eight years ago,' Tony said, catching Cho's gaze, 'there were just over three hundred patients. That was bad enough. Now there are more than two thousand. All of them children, sent here from every world in the Commons. And all of them will die here, for want of a cure.'

Orelolu greeted them at the landing stage and took them up to his office, where he and several staff members explained that the clinic had been founded by Ayo after the death of her eldest son, and gave a short description of its work and research programme. Cho sat through this quietly, but said at the end that he was pleased to see that they were using randomised trials. 'A lot of what you people call science is indistinguishable from magic. Claims of secret knowledge and special talents, all kinds of weird rites and ceremonies, and so forth. It's so rare and refreshing to find this kind of old-school methodology out here. Hopeful, even.'

'Aunty Jael must take most of the credit for that,' Orelolu said. 'She devised the experimental programmes. But despite all our work, we still have no idea what causes sleepy sickness, or how it is transmitted. And although we have prolonged the lives of some of our patients, we have yet to cure a single one.'

'That is why your work is so important,' Tony told Cho. 'We hope that it will give Orelolu and his crew a new direction.'

As they set out across a covered walkway that swooped above the river, linking the stark cube of the administration block with the accommodation domes, Orelolu took Tony's arm and said, 'I hear that you have moved out of the Great House and moved in with Danilo. Is it love, or just a silly stunt to piss off Opeyemi?'

'I can assure you that there is nothing silly about it.'

'You shouldn't use the boy to score petty points, Tony.'

'You set us up, cousin. And I am glad, now, that you did. And grateful. But frankly? Our relationship is none of your business.'

'Then why did you bring him here to rub my nose in it?'

'This visit was Danilo's idea, actually. And it was also his idea to come along. I told him that he would see things that might break his heart; he said that if he shed a tear or two it would help my pet wizard to understand the reality of this. He is tougher than he looks.'

'Even so, he is just an ordinary kid,' Orelolu said. 'Suppose Opeyemi decides to get at you by hurting him?'

'I will make sure he won't,' Tony said. 'Oh, and by the way? The sex is amazing.'

They entered an observation cubicle raised high in the side of one of the domes. Below, fifty or so children shambled about the black-sand floor. Some dressed in pyjamas or cotton gowns, some naked. Some moving in little groups, some following solitary paths, some standing still, staring off at something beyond the walls of the dome.

All were pre-adolescents between ten and fourteen, and all were in the second stage of sleepy sickness. To begin with, sufferers began to sleep for longer and longer, eventually passing into a state of unconsciousness that lasted for as long as forty days. Most woke and showed no other symptoms, but one in a hundred developed aberrant behaviour similar to sleepwalking, becoming increasingly withdrawn until at last lapsing into a catatonic state and shortly afterwards dying.

Orelolu told Cho Wing-James that the patients in this dome were local children whose parents had volunteered them for tests and experimental drugs and other treatments. Therapies developed here, he said, were used to treat children of parents who could afford to send them to Skadi.

'So basically, the rich kids benefit from their suffering,' Cho said, seeming more amused than angry.

'And the local children benefit from care they could not otherwise afford,' Orelolu said.

'I guess I have a hard time understanding it because we don't have your kind of social hierarchy on Earth,' Cho said. 'The honourable families thing, and so on. But you'd have a much bigger sample group, and a better chance of finding an effective treatment, if all of your patients were treated in the same way.'

'We hope that your work will give us a much better chance of finding a treatment that would benefit everyone,' Tony said.

'Including your family,' Cho said. 'A cure for sleepy sickness would be worth a tidy sum.'

'Perhaps we would give it away, increasing our reputation instead of our wealth,' Tony said, and half-believed it. The clinic was a reliable source of off-world income, but a selfless act would do more to repair the damage to the family's standing amongst the other honourable families than any amount of money.

Orelolu picked up the thread of his lecture, telling Cho Wing-Jones that sleepwalkers kept in isolation soon died. They were obligately gregarious, he said, forming gangs or tribes with unclear affiliations, marking their territories with piss and daubs of excrement, stronger gangs attacking weaker ones, weaker ones attacking singletons. The aggression was mostly low-level but sometimes flared into serious fights. Sleepwalkers could be badly injured if hands controlled by the clinic's staff failed to intervene quickly enough.

'But at least the sleepwalkers' behaviour has counterparts in ordinary human society,' Orelolu said. 'The final stage is worse because that is where the real madness lurks. Let me show you.'

Another dome, this one cupping a bell of dim red light, its floor a maze of crooked tunnels pieced from scraps of plastic and foam sheeting. The patients who inhabited this maze were in the terminal stage of their illness. They spent their time entirely inside their tunnels, rebuilding them from within and daubing them with patterns made from their own excrement.

'We have been able to extend the sleepwalking phase of the illness by several months, but every patient eventually enters the final catatonic stage, and its course is remorselessly swift,' Orelolu said, and called up images of naked and emaciated children, blank faces under tangles of filthy hair. Eventually, they fell into a permanent stupor, he said. They stopped eating and drinking; even if they were force-fed and attached to drips they quickly died.

Tony felt the same queasy mix of pity and disgust that had gripped him during the long weeks he'd spent as an intern at the clinic, part of his education in the family business. The sleepwalkers were children, but they were no longer human. They were running an alien algorithm in their brains. They were trying to express alien thoughts, alien behaviour. Whatever they had once been had been fragmented, overwritten. You never got used to that.

Danilo put his arm around Tony's shoulders, asked him if he was all right.

'I'm remembering how it was when I worked here. Nothing seems to have changed.'

Lancelot Askia was staring at them, his fists jammed in the slant pockets of his leather jacket, his pistol holstered at his hip. Tony stared back until the man looked away.

'Let me try the thing we discussed,' Danilo said, and stepped away and turned his back, standing quiet and still while Orelolu told Cho Wing-James about the characteristic long slow waves in the brains of sleepwalkers about to enter the catatonic phase. With his back still turned, Danilo began to sing a slow, aching song about a mother who gave up her sick son to the clinic and came to visit him every day, until at last she realised that she no longer remembered what her son had been like before he had fallen ill, and wished that she had never come at all. He sang with his fists clenched and quivering under his chin, his clear voice resonant in the small space. Tony and the others even Lancelot Askia, his arms folded sternly across his chest listened in silence. When the song ended and Danilo turned and sketched a small bow, Cho Wing-James gave Tony a long, thoughtful look before returning to the discussion about the sleepwalkers' neural activity.

The next day, in Aunty Jael's laboratory, the wizard told Tony that his crew wanted to make another attempt to crack the Ghajar algorithm they had isolated from the magnetite arrays. 'We will run copies in the ablated shells of a wide variety of eidolons, and compare their behaviour with controls containing native algorithms. The differences between Ghajar hybrids and controls will help us understand how to control the algorithm. And then, hopefully, we will be able to use it to explore the archival genetics.'

'You are still assuming the algorithm is a translation tool,' Tony said, with the sinking feeling that this was another frivolous diversion from the main task.

'If it turns out to be something else, we will go back to trying to build our own translation tool,' Cho said. 'But this could be the kind of quick and dirty fix you have been urging us to try.'

The experiment was as strange and solemn as an ancient religious ritual. The lights in the work space were dimmed. The bubble aquarium tank that housed the stromatolites glowed like a cauldron. Flickering columns of glyphs cascaded through windows as the wizards, robed in their white coats, chanted obscure instructions and readouts, and in the centre of their rough circle the smoky shadows of ablated eidolons flickered as the Ghajar algorithm was downloaded into them. Up in the walkway with Aunty Jael's hand, Tony held his breath, felt his blood tingle and his hair stir. But the eidolons remained stubbornly inactive: either the interface protocols were incorrect, or the algorithm the wizards had inserted into them was so badly corrupted that it was no longer functional.

Cho Wing-James dismissed the failure. 'We have learned what not to do,' he said. 'Next time we will do better.'

'Soon there won't be time for a next time,' Tony told him.

'Unfortunately, we are not in the miracle business.'

'That's a shame. Because if you want to stay in business, a miracle is exactly what you need.'

13. Code Farm.

Lisa meant only to knock back a few stiff ones to calm herself and numb the feeling of the ghost at her back, but of course that wasn't how it ended up. She woke on her couch sometime the next morning. The empty bottle on the tile top of the coffee table; the parched-mouth pinch-skulled hangover; the black fog of remorse and self-loathing. She managed to feed Pete and check the hurklins, then collapsed on her bed and dozed into the afternoon, waking with a stab of unfocused panic that crystallised into the realisation that she'd missed her appointment with Bria at the code factory. She used her piece-of-shit phone, cursing its nannying autocorrect, to send a text she'd come down with some twenty-four-hour bug, could she come in tomorrow, same time? and then hauled her sorry carcass into the shower. Bria replied while she was in there, confirming that tomorrow was fine, asking how she was. Convalescing, Lisa texted, not wanting to get into a conversation, made a pot of coffee and choked down a couple of slices of toast, and used her phone again, found there was an open meeting that evening in a church basement in Three Rocks.

On the drive over she steeled herself to confess her lapse, but lost her nerve and blurted out a lame apology when the chairperson took her aside at the beginning of the meeting and asked if she wanted to speak. She sat at the back and listened to the testaments of two volunteer sinners, left as soon as she decently could, and cursed her stupidity and cowardice all the way back home. Her lapse had badly frightened her. Reminded her that she was always just one drink away from reverting to her bad old ways, hiding inside a bottle, using booze to numb the inescapable presence of the thing in her head. She would atone by rededicating herself to finding out everything she could about the cause of the breakout that had killed Willie and the others. She would avenge his death by defeating her own ghost. Every day was day one. Every day you started over.

So the next morning she rose at dawn and spent three hours mucking out the hurklin pens and topping up the dry-feed hoppers and checking the water dispensers. They looked more like ambulatory oysters than tortoises, hurklins, perched on random arrangements of unpaired peg-like legs that made soft clickings as they shifted about. Now and then feathery sense organs flickered from under the margins of their shells, tasting the air like snakes' tongues; strings of crude, crystalline eyes were set in the leading edges of their shells, but they mostly found their way by taste and touch. There were almost a hundred of them in the pens, some standard stock, some part of a breeding experiment, crossing a big old male she'd bought from her one of neighbours with selected fresh-caught females from a guy over in Stone Creek. The first-generation crosses included three females with deep green shells marked with pleasingly random swirls of black. Lisa was planning to inbreed them with one of their brothers to see if their patterns stayed true.

After she had cleaned herself up, she drove into the city for the second time in three days, pretty much a record. Pete rode on the passenger seat, happily sticking his head into the slipstream. She'd asked him one time why dogs did that, and he'd told her it was fun, she should try it.

The code farm was in a business park halfway across town from the Alien Market. Inside its anonymous box a clutch of egg-shaped work pods were set out in an eight-by-four grid; the servers and a chill-out area were tucked under the platform that supported the conference room and Bria's glass-walled office. No basketball hoops, table football, air hockey or antique arcade machines, none of the testosterone-fuelled competitive atmosphere and raucous bonding rituals of most code farms, which exploited a transient population of young, mostly male coders by working them remorselessly for two or three years and replacing them with new recruits after they burned out or were flamed by exposure to raw algorithms. Bria employed more women than men, gave them long-term contracts with benefits, shared out bonuses from exploitable finds, encouraged her coders to decorate their pods according to individual taste. One had been made over into a replica of a spaceship cockpit; another was lined with a thin shell of polystyrene carved and painted like antique stone; the one that Bria and Lisa commandeered (from a young woman who told Lisa that she had been inspired to become a coder when she'd studied sandbox code at college, which made Lisa feel like a relic from deep time) was tiled with picture postcards from Earth anodyne views of beaches, mountains, monuments, city streets and parks and little vitrines containing robots dressed in a variety of national costumes. It was at once knowingly kitsch and deeply nostalgic.

Lisa and Bria closed up the pod, activated its Reynolds trap and deployed the security protocols, worked their way through checklists and alerts. The soft green glow inside the shuttered pod and the ozone whiff of the humming trap were calmingly familiar, somewhat abating Lisa's uneasy mix of guilt and shame. Bria hadn't mentioned yesterday's missed appointment beyond asking Lisa how she was feeling, but Lisa suspected that her friend knew that she'd taken a tumble off the waggon. It was an echo of her paranoia from the bad old days, when she'd worked zero-hour contracts in corporate code farms and sneaked carefully calibrated doses of shine during her shifts, and put a certain distance between the two of them.

At last, Bria activated the multi-spectrum scanner and told Lisa that she should do the honours. Lisa snapped open the little acrylic box and used silicon tweezers to pluck the tessera from its nest of cotton wool and set it in the foamed-plastic cradle.

It didn't look like anything special. A small flat chip of tile, roughly rectangular, surfaced with a dark grey sheen that had flaked off along one edge to reveal a tangle of fine black threads and a fugitive glitter of micronodules in a ceramic matrix. No different to the thousands of tesserae scattered across the walls of tombs in the City of the Dead in patterns that no one had been able to prove were anything other than random.

Lisa angled the Reynolds trap over the cradled tessera and with delicate concentration advanced the ball of the ultrasound probe until it kissed the smooth grey surface. Checked the frequency and timer settings, touched the on/off icon.

Most tesserae were inert. Some, triggered by the proximity of animals, biochines or humans, tickled optic nerves and generated hazy glimpses that might have been fantasies or fragments of the lives of the Ghostkeepers, the Elder Culture that had built the City of the Dead. And a few contained active intelligences. Ghosts, eidolons. But no eidolon appeared when the probe sang its mosquito song. Instead, the tessera was immediately enveloped in a flowing silvery-grey fog. Lisa believed that she could see movement in there, but it was hard to make out what it was. For a long moment, the rest of the world folded into the blind spot where her ghost lived . . .

The timer shut off the ultrasound probe; the flow vanished. Lisa tried to blink away silvery after-images. Her eyes prickled hotly and she felt the stab of an incipient headache.

Bria said, 'Are you okay?'

'I saw something. Like fog, or water . . .'

Lisa wondered if Willie had seen it, too. She watched eels of phantom light swim through the dim air of the pod while Bria ran through checks on the sandbox, finally announcing that the mirroring had been successful and bringing up the looped playback on the big 3D screen.

The code's graphic display was simpler than most, appearing as the same kind of silvery currents that had briefly enveloped the tessera, but with far greater resolution. Lisa could see rippling moire patterns in the flow now, like the play of sunlight on white sand at the bottom of a shallow sea. A Cartesian grid distorted by continuous coordinate transformation. And she was beginning to see repeating elements emerge in the fractal complexity, although the overall pattern seemed to be endlessly variable. She remembered a quote about architecture and frozen music. But this was moving, liquid, alive.

Bria brought up a wire-frame model of the grid, said that the initial results from decompiling, pattern matching and reverse lookup had already located several points of glancing similarity with Ghajar narrative code. 'I guess Carol Schleifer was telling the truth. But no one has ever found this stuff in a tessera before.'

'Run it again,' Lisa said.

There was something compelling about the rippling patterns rolling through the screen. A weird hypnotic beauty. After a little while Lisa glimpsed a flash of movement, as if something had momentarily come into focus, there and gone. She leaned in, trying to spot it again, and there it was, a brief distortion in the flow, dividing it as a fish divides a river current, blinking out as suddenly as it had appeared.

'There!' she said. 'Did you see that?'

Bria hadn't. Lisa asked her to rerun the last thirty seconds of the playback, pointed to the anomaly when it reappeared.

'I'm not sure what I'm supposed to see,' Bria said. She was leaning side by side with Lisa, bright lines gliding across her face.

'There's a kind of displacement in the flow,' Lisa said. 'Let me loop it.'

She saw, as the loop ran over and again, chains of flashes flickering in the anomaly's wake. Bright vortices emerging, spinning away in the silvery stream. She froze the playback, pointed them out to Bria.

'I think I see something,' Bria said. 'But maybe only because I want to see it.'

They seemed very obvious to Lisa. Cream-into-coffee swirls that flowed across the Cartesian grid without distorting it. Fingerprints on a blank page. Gas clouds birthing stars. Ghostly jellyfish caught in a rip tide . . .