She needed to run the real thing again. She needed the data from Bria's decompiling, pattern matching and reverse lookup. She needed to sleep, but knew that she couldn't. She needed a fucking drink and swore that she wouldn't. Instead, she opened another bottle of Club-Mate and began to read up on Ghajar algorithms.

The Ghajar had been a gypsy species that had left almost no trace of its civilisation or culture apart from its ships and a few so-called landing towers. Most of their ships had been abandoned in orbital sargassos, but several crash sites had been identified on First Foot and other Jackaroo gift worlds. Some archaeologists believed that the Ghajar had beached their ships much as whales and smaller cetaceans, because of disease or panic or suicidal ennui, had stranded themselves on beaches on Earth. Others said that the crashed ships were casualties in a war between factions of the Ghajar, and suggested that so-called mad ships recently discovered in a remote sargasso, which killed or drove crazy anyone who approached too closely, were weapons which had been used in that war.

One thing was certain: all Ghajar ships were infested with algorithms, quantum stuff embedded in the spin properties of fundamental particles in the molecular matrices of their hulls, riddled with errors and necrotic patches that had accumulated during millennia of disuse. Coders analysed and catalogued the algorithms, stitched viable fragments together, and spent hours and days trying to get them to run in sandboxed virtual spaces.

Ghajar ship code had played a pivotal role in the development of various kinds of quantum technology and had helped to solve four of the so-called hard mathematical problems; one of Ada Morange's companies had used it to develop the AIs that acted as interfaces between the ships and their human pilots. But Ghajar narrative code was another country. Unmapped, untranslated, incomprehensible. Lisa googled some scholarly articles, most of them by a professor at Peking University, no doubt the researcher Carol Schleifer had mentioned. Lisa had trouble following his deep theoretical analyses, but the conclusions were plain: no one knew what narrative code did, what it contained, or how to read it. And no one ever seemed to have observed the distortion she'd seen, either.

It was four in the morning. She was wired but bone-tired, and was still seeing little flashes in the air. She crashed for a couple of hours, woke around dawn and fed Pete, brewed a pot of coffee and whizzed two chopped bananas with almond milk in a blender and drank her breakfast while watching the looped playback just one more time. Okay, another.

It was too early to phone Bria. Lisa called anyway. It went straight to voicemail.

She was in the barn, checking on the hurklins, when a car horn sounded out in the yard. Sheriff Bird was standing at the gate, and a black SUV and a powder-blue Range Rover were parked behind his tan patrol car. The geek police were back.

16. Conceptual Breakthrough.

Tony went straight from church to the laboratory . Junot Johnson intercepted him outside the workshop, saying that there had been a development.

'The wizards have been working all through the night,' he said. 'They believe they have made what they call a conceptual breakthrough.'

'Is this something real, or some kind of theoretical business no one else would ever be interested in?'

'Maybe one, maybe the other,' Junot said. He had a grainy, bloodshot look: he must have been up all night too. 'They're working on that Ghajar stuff again-'

'After I told them to give it up? Has time started running backwards here?'

'I know, Mr Tony. They're a stubborn lot. But this time they may be on to something. That last experiment? The blue light you told me about? They think it was some kind of eidolon. They think it's done something to their heads, lets them see stuff they couldn't see before. They think that it could help them to read the stromatolite data.'

'What kind of eidolon? Is it harmful?'

'I don't know. They're more interested in what it does than what it is.'

'I could be infected, too. So could you.'

'It's possible, Mr Tony. Although if you remember, I was in the city at the time, buying elements for their maker.'

'You should have told me what they were doing from the very first,' Tony said. He was angry and scared. First Opeyemi, and now this. It was as if everything was spinning away from him. 'I have just had a very difficult conversation with Opeyemi I am certain Lancelot Askia told him all about this. But you waited until now . . . It's unacceptable, Junot. Completely unacceptable.'

'I realise that, Mr Tony. And I'm sorry,' Junot said, with a hangdog look of contrition.

'"Sorry" will not fix this mess. But there is something you can do. Opeyemi told me that someone is sending clandestine messages off-world. He believes it is one of the wizards. If he is right, we must deal with the traitor straight away. Are they working on this so-called breakthrough right now?'

'They're all in the work space, yes.'

'Good. I want you to search their accommodations. Look for anything that could be used to connect to the city net. It might be a phone, it might be some sort of homebrew device. Turn everything upside down and inside out. If you don't find anything, I want to be certain that it is because there is nothing there, not because you fucked up again.'

'I will do my best. Although the man Askia searches their stuff regularly, and he hasn't found anything I know of.'

'Yes, because he could have planted something. Because this traitor may not exist outside of Opeyemi's scheming.'

'I don't follow, Mr Tony.'

'My uncle knows about this breakthrough, and will have guessed that I would want to use it to argue for an extension of the council's deadline. So he may have had his man plant damning evidence that one of the wizards is a traitor, and when I fail to find it he will accuse me of incompetence. You see it now?'

'Clear as ice, Mr Tony.'

'Then get to work. Search every square centimetre of the wizards' accommodations. Meanwhile, I will get up to speed on this discovery of theirs.'

The wizards were clustered around a big window in the work space. One of Aunty Jael's hands stood behind them this one tall and very thin, clad in polished black plastic that reflected a stream of silvery light waterfalling through the window. Lancelot Askia sat in his usual place in the kitchen area, watching everything with sleepy insolence.

The hand did not turn as Tony approached. Instead, an image of the face that Aunty Jael chose to present to the world floated around the screen that ringed the flat-topped cylinder of its head, saying, 'Something wonderfully interesting has happened.'

'So I heard,' Tony said, and asked Cho Wing-James if he had cracked the archival genetics.

'Not exactly,' the wizard said, running his fingers through his disordered mass of hair. 'But I think that we have cracked something that can.'

His explanation came in an eager rush of technical terms. Tony held up a hand to silence him, asked Aunty Jael for a summary. It seemed that the storm of virtual light had contained densely packed sequences of information that had interacted with the wizards' visual cortices and printed copies of an eidolon in their brains.

'The eidolon is a kind of translation tool,' Aunty Jael said. 'The Ghajar appear to have used it to hack into the archival genetics via the stromatolites' transmission system, extract data, and render it into so-called narrative code.'

'That is what we are studying now,' Cho Wing-James said.

'And can you translate this narrative code into something I can understand?' Tony said.

'That's a very interesting question,' Cho said, and opened a small window that displayed a kind of starburst with lines of unequal length radiating from a central point. The wizard set it rotating, asked Tony if he had ever drawn something like it, or if it had featured in any of his dreams.

Tony felt a clammy twinge of unease and said, 'You had better tell me exactly what this eidolon has done to you.'

'To begin with, it helps you see patterns in the narrative code,' Cho said. 'Eli and Rael saw them first.'

'We were running the code in different configurations, and it suddenly popped out at us,' Eli Tanjung said. She was the youngest of the wizards, a solid, solemn young woman with glossy black hair and a trace of a moustache on her upper lip. A plastic circlet spiky with plug-in circuitry was clamped around her head.

Rael Manzano also wore a circlet. 'We could not believe what we saw,' he said. 'We stared at it for an hour at least. Such unexpected beauty!'

'I believe a demonstration is in order,' Cho Wing-James told Tony. 'We'll run it from the beginning, let you see for yourself.'

The silvery flow in the big window blinked out, resumed. At first, Tony saw only a uniform stream of mercury light, but then he felt a weird moment of doubling, as if he was watching himself watch the window, and began to make out knots and vortices like unstable whirlpools, or the teardrop shapes that water currents made in rivers when they divided around obstacles. The patterns were everywhere he looked, and there were patterns within the patterns. An eternal silver braid flowing past, beautiful and compelling . . .

'That's enough, I think,' someone said, and the window blanked and he came to himself with a start.

'You see?' Cho said. 'You see?'

'I saw something,' Tony said. 'But I don't know what it was.'

'Similar patterns were discovered more than a century ago,' Cho said. 'Only those infected with a specific and very rare kind of eidolon can see them. Apparently, that is what infected us.'

'And it has spoken to us,' Eli Tanjung said. 'It has shown us the way.'

'Some of us have felt a compulsion to draw diagrams similar to the one I showed you,' Cho said. 'We believe that it is something encoded within those patterns. Its meaning isn't clear, not yet, so we are hoping to stimulate our eidolons into providing us with more examples.'

That was what the wizards had been doing when Tony had arrived. Taking turns to wear circlets that with pulsed magnetic fields poked and pried at the eidolons in their heads, trying to stimulate them, trying to make them reach into the narrative code and pull out something comprehensible. If the stromatolites contained data relevant to sleepy sickness and other meme plagues, Cho said, tugging at stray strands of his hair, this was their best chance of finding it.

Tony told Aunty Jael again that he wanted a word in private. When he climbed up to the balcony, pushing through the dull hum of its privacy screen, another hand was waiting there one of the skinny white-skinned hands, this one with a stencilled 3 on its chestplate.

'Just how dangerous is this eidolon?' he said.

Thinking about it made the inside of his skull itch.

'It is hard to say. However, it appears to interact only with Ghajar narrative code.'

'I suppose that I'm also infected. As is Lancelot Askia.'

The idea that his uncle's man harboured a copy of the eidolon gave Tony a thin satisfaction.

'I have tested the neural activity of the wizards,' Aunty Jael said. 'All of them possess the characteristic signature of the eidolon. If you like, I could also test you. As for Mr Askia, I doubt that your uncle would give me permission.'

'What about you? Are you infected?'

'Alas, no. My mind is fixed. Also, the eidolon appears to have infected only those in the immediate vicinity of the light storm. Several of my hands were caught up in it, but my mind was, of course, elsewhere.'

Tony remembered when he had first seen Aunty Jael's true self. He had been eight, about to become her pupil. Ayo had taken him down to the basement of the laboratory, to a small room lit by a warm blood-red glow, with a ladder of shelves holding what looked like the spines of printed books. His big sister had put on white cotton gloves and pulled out one of those books, showed Tony that it was a slice of brain just a few nanometres thick in a rectangular leaf of grainy plastic.

'The plastic contains circuitry that infiltrates the laminated cytoarchitecture,' Ayo had said, holding the plastic leaf in gloved hands. 'And the circuitry of each leaf is connected to all the others. The brain provides the template for the mind that is generated by all of this, and the circuitry animates it. All this, everything on these shelves, is needed to support an imperfect simulation of a single human mind. Remember that, little brother. Aunty Jael may appear cleverer than us, but that is only because she is able to think faster. It is a shallow kind of thinking, and her viewpoint is fixed. Unlike us, she is unable to change. And that, in the end, is what counts.'

Tony said now, 'So far all it has given us is that funny diagram. And we do not know what it means.'

'Not yet,' Aunty Jael said.

'And even if they can use this eidolon to translate the stromatolite data, they may not find anything that can be used to understand and treat sleepy sickness.'

'I am cautiously optimistic,' Aunty Jael said.

'But it isn't anything I can take to the family council,' Tony said. 'And there's another problem. The thing I came here to tell you.'

He quickly explained Opeyemi's story about one of the wizards sending messages, his belief that it was a ploy to undermine the little authority he had. But when he threw the link that his uncle had given him to Aunty Jael, expecting her to find something that would prove that the clandestine messages were fake, she said that they not only appeared to be genuine, but packet analysis showed that they had originated in her laboratory.

'Do you know who sent them?'

'I'm afraid not.'

'How it was done? How anyone could hack the common exchange from here? I thought you had locked down comms.'

'There are no direct lines, but there are a number of devices and utilities that communicate their status with central services. Someone appears to have used one of those connections to tap into the city net, and then reach out to the common exchange. Fortunately, a unique numerical string is inserted into every communication with central services, identifying the device that sent it. These messages were all sent from the same place: the power transformers.'

'Are you certain?'

'While we have been discussing this, I have used one of my hands to locate an unauthorised device attached to the downlink with central services. It is accessed by a simple transceiver, similar to those used to control various probes in the stromatolite aquarium.'

'Show me.'

Aunty Jael's opened two small windows, one showing a small bead inside a cable junction box, the other the X-ray image of the scrap of circuitry it contained.

'I looked for fingerprints but found none,' she said. 'Likewise with DNA. Traces of talc suggest that the person who built and installed it wore gloves.'

'So we know how these messages were sent, but we still do not know who sent them.'

'Correct.'

'I don't suppose you can break the encryption.'

'Oh, I'm certain that I can. But it will take time.'

'How much time?'

'Less than that left before the heat death of the universe,' Aunty Jael said.

'Is that supposed to be a joke?'

'I thought it very like one.'

'If I were you, I'd stick to wizard work,' Tony said.

'Your culture does not recognise me as a human being, and I was long ago stripped of all the rights that human beings enjoy,' Aunty Jael said. 'I became a chattel, and was purchased by your grandfather for my skills and expertise, not for who I am or who I once was. Since then I have always carried out my instructions without complaint, have always tried to do my best for your family. I have especially enjoyed working with you, Master Tony. Your adventures have been thoroughly stimulating, reminding me of my younger self and giving me a sense of freedom I thought I had long ago lost. And I hope that my endeavours on your behalf have given you some small respect for my judgement, and that you will listen carefully to my advice now. Because I have a very good idea about how I can help you catch this traitor.'

Later, Tony realised that Aunty Jael had been warning him about her own plans. That her little speech was both a confession and a boast. But at the time, he thought that it was a plea to be taken seriously. And the thing was, her idea did seem like a good one. Simple, direct, and something they could try at once.

17. Under Caution.

Lisa was fingerprinted and photographed in a clinical room somewhere in the basement of the UN building, the inside of her cheek was scraped for a DNA sample, and she was taken up in a freight elevator to an open-plan office and left in a small side room painted Disney Princess pink. Sitting in a plastic chair bolted to the floor, handcuffed to a battered table like an actual criminal. Headachy light from a buzzing fluorescent circlet bounced off the pink walls. Someone had scratched their tag, Bullpup, in wonky Gothic lettering in the plastic tabletop. The door was slightly ajar. She could glimpse people coming and going in the office, hear clipped exchanges on a police radio.

She tried a couple of breathing exercises to calm herself.

She tried not to stare at the black eye of the camera up in one corner of the ceiling.

After about twenty minutes, the agent who had escorted her through booking and processing returned and asked if she wanted anything to drink.

'I think this is where I say I'd like to speak to a lawyer.'