Geoffrey grimaced. *You make it sound like I'm some bizarre medical specimen, pickled in a bottle somewhere.'

*I don't know how many times I've told Jitendra what you do,' Sunday said, with an exasperated air. *I mean, it's not like I was talking about some obscure second cousin twice removed or anything.'

Around them the graffiti reconfigured itself endlessly, except for mouse-grey patches where the paint had failed or scabbed off. Graffiti was very quaint, Geoffrey thought.

*So, anyway: elephant cognition,'Jitendra said decisively. *That sounds pretty interesting. Where do you stand on Bayesian methods and the free-energy principle?'

*If it's free, I'm all for it.'

*Not really a theoretician, our Geoffrey,' Sunday said. *At least, theoreticians don't usually make a point of smelling like elephant dung, or flying around in two-hundred-year-old deathtraps.'

*Thanks.'

She wrapped an arm around his waist. *Wouldn't want him any other way, of course. If it wasn't for my brother, I'd feel like the only weird member of the family.'

She came to a stop next to a patch of wall where the muddy brown background coloration of earlier graffiti layers had been overpainted with a trembling, shimmering silvery form, like the reflection in water of some complex metallic structure or alien hieroglyph. Blocks and forms of primary colours were beginning to intrude on the silver, jabbing and harassing its margins.

Sunday pushed her finger against the wall and started reasserting the form, pushing it back out against the confining shapes. Where her finger pressed, the silver turned broad and bright and lustrous. *This is one of mine,' she said. *Did it five months ago and it's still hanging on. Not bad for a piece of consensus art. The paint tracks attention. Any piece that doesn't get looked at often enough, it's at the mercy of being encroached on and overpainted.'

She pulled back her finger, which remained spotless. *I can redo my own work, provided the paint deems itself to have been sufficiently observed. And I can overpaint someone else's if it hasn't been looked at enough. I'd hardly ever do that, though a it's not really fair.'

*So this is Sunday Akinya, literally making her mark,' Geoffrey said.

*I don't sign this stuff,' Sunday said. *And since I mostly work in sculpture and animation these days, there's not much chance of anyone associating a piece of two-D abstraction with me.'

Geoffrey stood back to allow a luggage-laden robot to speed past.

*Anyone could've seen you do it.'

*Most wouldn't have a clue who I am. I'm a small fish, even up here.'

*She really is a struggling artist,' Jitendra said.

*And half the people who live here are artists anyway, or think they are,' Sunday said, ushering them on again. *I'm not an Akinya here, just another woman trying to make a living.'

As they approached the end of the graffiti-covered corridor, Geoffrey sensed that it was about to open out into a much larger space, the acoustics shifting, the feeling of confinement ebbing. There was even a hint of a breeze.

They emerged high up on one side of a vast flat-roofed cavern. Easily two kilometres across, Geoffrey guessed. Bright lights gridded the slightly domed ceiling, drenching the entire cavern with what appeared to be a simulacrum of full planetary daylight.

Buildings crammed the space, tight as a box of skittles. Many of them reached all the way up to the ceiling and some even punched through. Towers and cupolas and spires, spiralling flutes and teetering top-heavy helices, baroque crystalline eruptions and unsettling brainlike masses, and everything shimmering with eyeball-popping colour, hues and patterns that flickered and shifted from moment to moment, as if the city was some kind of ancient computer system locked in an endless manic cycle of crash and reboot. The lower parts of the buildings, where they were accessible from street level or elevated walkways, were gaudy with layers of psycho-reactive graffiti. The upper levels carried active banners and flags or daubs of fluid, oozing neon, alongside tethered balloons with illuminated flanks.

*Did you remember to book ahead?' Jitendra asked.

*It's a Thursday,' Sunday said. *It won't be heaving.'

Down in the congested lower levels Geoffrey made out bustling traffic, electric vehicles shuffling through near gridlock like neat little injection-moulded game pieces. There were cyclists and rickshaw drivers and piggyback robots. Human and mechanical motion, everywhere.

Sunday led them across a black ironwork bridge. It carried a wooden-floored promenade with perilously low railings, interrupted here and there by booths and stands with striped canvas awnings.

*That's the Turret,' she said, indicating the structure at the other end of the bridge. *Best views of the cavern. Hope you've worked up a good appetite.'

Inside the Turret it was all organic pastel-coloured forms, enlivened with glass and porcelain mosaics set into umber-coloured stucco. Sunday had led them directly to a window alcove shaped like some natural cavity worn away by subterranean water erosion. Only after several minutes of dutiful observation was Geoffrey able to confirm that the view was creeping slowly past. Sunday told him that the machinery making the restaurant revolve had been repurposed from an abandoned centrifuge. The bearings were so icily smooth it felt as if the rest of the universe was doing the turning.

He was on one side of the table, Sunday and Jitendra on the other. Sunday had ordered a big bottle of Icelandic Merlot before Geoffrey had even put his bag down, wasting no time in charging their glasses. They made small talk over the appetisers, Sunday pushing him on his current romantic entanglements, or lack thereof, asking him if he had heard from Jumai lately. He told her that Jumai had chinged in on the day of Eunice's death.

*Sounds very exciting, what she's doing. And quite dangerous,' Sunday said.

*They pay her well,' Geoffrey said.

Ordinarily he'd have been uneasy talking about an old girlfriend, but at least it kept them off the one topic he didn't want to go anywhere near.

*More wine?' Sunday asked, when the waiter came to take away their empty appetiser plates.

Jitendra levelled a hand over his glass. *Need a clear head tomorrow. Robot Wars.'

Geoffrey looked blank.

*Jitendra's a competitor,' Sunday said. *It's a thing he does. We'll go out and see it tomorrow, the three of us.'

*Something to do with free energy?' Geoffrey asked, keen to latch on to a topic that would keep them off the real reason for his visit.

*Something else entirely.' Jitendra lowered his voice, as if he was in dread danger of being overheard by the other diners. *Although June Wing will be there, I think.'

*You work for Plexus?' Geoffrey asked, recognising the name.

*I do work for them,' he said, making the distinction plain. *They pay me to have interesting ideas, while at the same time recognising that I could never function in an orthodox corporate environment. They also give me far more creative latitude than I'd ever get working full-time in their labs. The upside is I don't really have deadlines or deliverables. The downside is I don't get paid very much. But we can afford to live where we do and I have a twenty-four-hour hotline to June that some people would kill for.'

*So this . . . free-energy thing a is that a Plexus research programme?'

*Not officially, because the whole point of free energy a at least in the sense that I'm interested in it a is to create human-level artilects. And that's obviously a fairly major no-no, even now.' Jitendra scratched at his dark-stubbled scalp. *But unofficially? That's a different kettle.'

*We found one once,' Geoffrey said. *Near our home. It tried to take over Sunday's mind.'

*She told me about that. What you encountered was an abomination, a military intelligence. It was designed to be insidious and spiteful and inimical to life, and it wasn't smart enough to have a conscience. But artilects could work for us, if we make them even cleverer.'

When the waiter arrived with their main courses there was the usual minor confusion over one of the orders. Geoffrey suspected that this reassuringly human touch was now firmly embedded in the service.

*Maybe that's not as easy as it sounds,' he said, *making machines smarter.'

*Depends where you begin.' Jitendra was already tucking in. *Seems self-evident to me that the best starting point would be the human mind. What is it, if not a thinking, conscious machine that the universe has already given us, on a plate?'

A queasy image of a brain, served up with salad and trimmings, intruded into Geoffrey's thoughts. He shoved it aside like an undercooked entree.

*Animal cognition, there's still work to be done. But the human brain? Isn't that a done deal, research-wise?'

Jitendra pushed his food around with enthusiasm. *We know what goes on in a mind. We can track processes and correlate them at any resolution we care to specify. But that's not the same as understanding.'

*Until,' Sunday said, *Jitendra comes along, with his world-shaking new ideas.'

*I'd take credit for them if they were mine,' Jitendra said. He inhaled a few hasty mouthfuls while holding up his knife to signal that he was not yet done talking.

Geoffrey decided that he rather liked Jitendra. And while Jitendra was talking, he didn't have to.

*Point is,'Jitendra continued, swallowing between words, *I'm not just doing this out of some deluded sense that the world gives a damn about a theory of mind. What it cares about are practical applications.'

*Hence the Plexus connection,' Geoffrey said.

*You've seen the claybot. That's the physical edge of things. There's also the construct, which Sunday has been involved with at least as much as me.'

*The construct?'

*Later,' Sunday said, smiling.

*And ultimately . . . there's a point to all this?' Geoffrey asked.

*We need better machines. Machines that are as smart and adaptable as us, so they can be us a or go places we can't,' Jitendra said.

Geoffrey's expression was sceptical.

*Look, you're going to meet the Pans at some point,' Jitendra went on. *They're our friends, and they have one point of view, which is that only people ought to be allowed to go into space. The flesh must inherit the stars; anything else is treason against the species. On the other side of the debate, you've got hard-line pragmatists like Akinya Space who will always send a machine to do a human's work if it's cheaper. That's why you've got umpteen billion robots crawling around the asteroid belt.'

*We're having dinner in a restaurant on the Moon,' Geoffrey said. *Isn't it a bit late to be worrying about who gets to go into space?'

*The reckoning's not over, it's just postponed,' Jitendra answered. *But the Pans are growing in strength and influence, and the industrialists haven't suddenly backed off from their dollar-eyed conviction that robots make the most sense. Sooner or later, heads are going to bash. Not around Earth or the Moon, maybe, but we're pushing into deep space now a Trans-Neptunian, the inner boundary of the Kuiper belt, and we've even got machines in the Oort cloud. That's where it gets stickier. If we're going to do anything useful out there, we'll need smart machines and lots of them. Machines that break right through the existing cognition thresholds, into post-artilect computation. Human-level thinkers that can live with us, be our equals as well as our workers.'

*You're not sounding any less scary than you were five minutes ago,' Geoffrey said.

*Look, in a thousand years, the difference between people and machines . . . it's going to seem about as relevant as the difference between Protestants and Catholics: some ludicrous relic of Dark Age thinking.' Jitendra gave a self-conscious shrug. *I'm not on the side of the machines or people. I'm on the side of the convergent intelligences that will supplant both.'

Geoffrey was leaning back in his seat, blasted by the G-force of Jitendra's conviction. *And this . . . free energy? It's a way of making better machines?'

*It may be,' Jitendra conceded. *Don't know yet. Too many variables, not enough data. The construct looks promising . . . but it's early days and I don't doubt we'll take a few wrong turns along the way. All I know is that we're unwinding two hundred years of orthodox robotics development and heading off in a completely different direction.'

*Bet that's what they really want to hear at the shareholder meetings,' Sunday said.

Jitendra picked at something stuck between his teeth. *It's harsh medicine. But June Wing, bless her, is at least slightly open-minded to new possibilities.'

*Especially if there might be a dazzling commercial return at the end of it,' Sunday said.

*Businesswoman first, a scientist second,' Jitendra said. *No sense in blaming her for that a she wouldn't have her hands on the purse strings otherwise.'

*Talking of purse strings,' Sunday said, brushing crumbs from the napkin she'd tucked into her collar, *something I've been meaning to ask my brother: did the cousins cough up any more money?'

Geoffrey blinked, attempting to marshal his swirling, wine-addled thoughts into some semblance of clarity. The question had blindsided him.

*The cousins?' he asked.

*As in Lucas and Hector. As in the men with the ability to end all your funding difficulties.'

Geoffrey poured some more wine and sipped before answering. *Why would they give me more funding?'

*Because you showed up at the scattering, because you acted like a good little boy and didn't get into any upsetting arguments.'

He smiled at his sister. *You showed up as well, and it's not like they started showering you with benevolence, is it?'

*I'm a lost cause; you're not completely beyond salvation.'

*In their eyes.'

Sunday nodded. *Of course.'

*I think some more funds might be forthcoming,' he said neutrally. *I obviously made a good case for the elephants. Now and then even hard-line Akinyas take a break from rabid capitalism to feel guilty about their neglected African heritage.'

*For about thirty seconds.'

He shrugged. *That's all it takes to transfer the funds.'

*Reason I asked,' Sunday said, stretching in her seat, *is that I wondered if you were up here for fund-raising purposes? It's not like you come here very often, and the last time a if I'm remembering rightly a it was definitely cap-in-hand.'

*I just thought it was about time I came up to see you. Are you going to throw a fit the one time I actually listen to you?'

*All right,' Sunday said, holding her hands up to forestall an argument. *I was just saying.'

Over coffee the conversation headed back into less treacherous waters: Sunday and Geoffrey trading stories about their childhood in the household, encounters with animals, encounters with Maasai, funny things that had happened between them and Memphis, Jitendra putting on a good impression of being interested and inquisitive.

When Sunday had picked up the tab and they went out onto the restaurant's circular roof, the air had cooled and with the dimming of the ceiling lights the nocturnal effect was complete. Not that there was any sense that the city was winding down for the night, judging by the continued traffic sounds, music, shouts and laughter billowing up from below.

Sunday pointed out landmarks. Older buildings, newer ones, places she liked and didn't like, favoured restaurants, disfavoured ones, clubs and places neither she nor Jitendra could afford. Or rather, Geoffrey thought, places that she chose not to be able to afford, which was far from the same thing. Sunday had spurned Akinya money, but that didn't mean the floodgates couldn't be opened at a moment's notice, if she ever changed her mind. All she would have to do is renounce her decadent artistic ways and agree to become a profit-sharing partner in the collective enterprise.

As, indeed, could he, just as easily.

*We're going that way,' Sunday said, pointing to a wide semicircular hole in the far side of the cavern wall. She was, Geoffrey realised, much less intoxicated than either of her two companions. He began to wonder, with a sense of dim foreboding, whether she had been softening him up for interrogation.

At street level they came out into some kind of all-night souk, a place of winding, labyrinthine passages roofed over with strips of tattered canvas and latticed bamboo. Food, animals, garments, consumer goods, cosmetics, surgical services and robotics parts lined the lantern-lit stalls and booths. Huge muscled snakes like coiled industrial ducting extruded from lurid green and yellow plastics. Jewel-eyed seahorses, dappled with spangling iridophores. Tiny, dollhouse-sized ponies, pink and blue and anatomically perfect. Vendors selling what Geoffrey at first took to be sheets of black, brown and pink textiles a dress fabric, curtains, perhaps a until he realised that he was looking at custom skins, vat-grown flesh sold by the metre. New skin, new eyes, new organs, new bones. Most of these commodities, being illegal elsewhere, must have been fabricated in or around the Zone itself. There was industry here, as well as artistry and anarchy. Like Dakar or Mogadishu, a hundred or more years ago: the dusty, squabblesome past that every clean, ordered, glittering African city was trying hard to put behind it.

They jostled through the souk's crowds. Jitendra spent several minutes digging cheerfully through plastic crates of salvaged robot parts, picking up a piece then discarding it, rooting out another, holding it up to the lantern light with narrowed, critical eyes.

*Watch your bag,' Sunday said as they waited for Jitendra to strike a deal. *Thieves and pickpockets abroad.'

Geoffrey swung the sports bag around, clutching it to his chest like an overpadded comfort blanket. *Really? I'd have thought most of your fellow citizens went through Mandatory Enhancement screening at birth, the way you and I did.'

*That's true,' Sunday conceded, while Jitendra continued his haggling, *but there isn't some handy colour-coded brain module labelled "the impulse to commit crime". What is crime, anyway? We might both agree that rape and murder are objectively bad things, but what about armed resistance to a despotic government, or stealing from the rich to feed the poor?'

*The last time I looked, there was a distinct shortage of both despotic governments and poor people.'

*Crime has a social context. In the Surveilled World, you've engineered criminality out of society using mass observation, ubiquitous tagging and targeted neural intervention. Good luck with the long-term consequences of that.'

Geoffrey shrugged. *Locksmiths find another line of work.'