"For what? Hang on." She looked away. "Will you guys slow down? Control, with your partner. Save your power for the bags."

There were m.u.f.fled sounds.

"Sorry," she went on. "It's hard for them to understand the difference, when to be a partner and when to be an opponent. So, what favour are you ringing up to ask?"

"Who are you teaching? Cops or kids?"

"Kids. I'm not on duty till twenty hundred. Here, take a look." A translucent image washed across the windscreen: children, aged from maybe eight to fifteen, with sparring gloves and headgear. "Doing some good."

"Yes, you are."

Some of the kids needed self-esteem, properly earned. Others needed to physically defend themselves. Petra and her friends taught for free.

"Huh. Mark, take over, w.i.l.l.ya?" The image shifted, her face filling the windscreen. "So you're after a favour. If it's a b.l.o.w.j.o.b you want, the answer's no."

"Jesus, Petra."

"But I know some nice guys who wouldn't mind"

"It's a missing kid."

"Official police case?"

"Uh-huh. Along with all the thousands of others on file."

"And you're taking a special interest?"

"Yeah. I'm putting together a ghost search, gait a.n.a.lysis, the whole thing."

Anyone who watched crime dramas knew how to use wigs, cap-veils, and changes of clothing to slip through surveilled crowds. Fewer would change the way they walked.

"And you want me to slip your little querybot into the London Transport net."

"You have authority to do that, Sergeant Osbourne?"

"Let's say it's not impossible. When's the code going to be ready?"

"A first cut tonight, if you let me have two attempts. Otherwise, I'm still gathering info. I'll have version two ready in the morning."

"Send that to me tomorrow, then."

A rough search tonight might save Richard a night on the streets. But this was her deal.

"Done."

"All right. Daniel! I said control, not miss by a mile"

Her image flickered out, leaving only the sight of concrete and shadow, an anonymous urban car park that could have been anywhere, impersonal as Richard Broomhall's bedroom.

Hey, kid. Where the h.e.l.l are you?

Yet in his mind's eye was not a teenage youth on London's streets, but a ten year-old girl with rice-paper skin, body intubated, surrounded by relentless machines that kept her organs working, however much they yearned to stop.

Where was the sense in any of it?

Silver sheets of rain were washing from the sky as he pulled in to the lay-by. Other cars hissed past on the dual carriageway, and good luck to them. He was going to stay parked until the worst was past. This was yet another flash storm in a year of storms and whirlwinds, the worst of driving conditions. No problem for Josh: with a few commands, he turned his windscreen into a full-on display, cranking up a programming environment with debugging and simulation panes, the lot. Unfurling a keyboard and coding glove, he set up his querybot as nested sh.e.l.ls, and began with the inference engine. Soon he was in programming Zen, absorbed in the code, sketching in prototypes and test harnesses, working fast because he knew these frameworks and face it, he was good.

Finally he paused, considered calling the shrink that Richard had seen, rejected the idea it would take a minimum of fifteen minutes to restore his thoughts afterwards, to get back in the zone then changed his mind again, and placed the call.

"h.e.l.lo. My name's Josh c.u.mberland. I'm working on behalf of Philip Broomhall."

On the windscreen, her coffee-coloured skin was translucent, the eyes somewhere between nut-brown and honey. She nodded, both smiling and serious.

"I've been expecting someone to call."

"Well, I'm not with the police, but I am investigating on Philip Broomhall's behalf. If you'd like to verify, I'm happy to wait offline."

"But would he accept a call from me? Tell me the name of the agent you're working through."

"You mean Geordie Biggs?"

"All right, Mr c.u.mberland. Now I don't know where Richard went, nor do I know the specific trigger that set him off. I do know there was an issue to be explored, bullying at school, and the more I think about it, the more relevant it feels."

"That's the kind of thing I hoped you could enlighten me with."

"You could step through the recording of our session, a.s.suming that will be a help."

"Um, yes, please. Transmit via any archiving format you like."

Her eyes seemed to keep growing larger.

"I'd rather meet face to face. There are nuances to pay attention to in the recording, behavioural signals to highlight, that kind of thing."

"OK. You're in Elliptical House, is that right?"

"Not this afternoon. I live in what some people call the smart end of Kilburn."

"I can meet you there." He looked at the side windows, rippling with water but no longer awash, as the storm lessened. "Your place, or a bar?"

"How about a restaurant? Do you like Jamaicanfood? Later, say at seven?"

"Perfect.""OK, I'm appending details. There's a red star on the map, highlights the place."

"Works for me."

"Look forward to meeting you."

The attachment pinged and opened as the comm pane closed.

Wow.

Broomhall blamed her, so she would want to deflect that, get Josh on her side. If she was genuine in wanting to help him find Richard, then the rest was irrelevant.

He realised he was staring where her image had been, as if trying to summon her back.

Bad idea. Concentrate.

But she was the first good thing to distract him for a long time.

Browns and oranges dominated the restaurant. Each table bore a bonsai palm tree. Josh smiled as Suzanne d.u.c.h.esne addressed the staff by their first names, and they responded likewise. A Jamaican waiter called Clyde seated them next to the wall, away from the other diners, giving them a quiet zone.

From her shoulder bag, Suzanne drew a portable screen and unrolled it, spreading it across the table. While they waited for drinks to arrive some kind of tea they made small talk: how long she had lived in Kilburn (four years), where he was staying (a budget Travelodge off the M4), and who would win the general election.

"Let's see." Josh looked down at the lifeless screen. "Sharon Caldwell is female, lesbian, an atheist rationalist with two PhDs. Then there's Billy Church, aka Fat Billy, man of the people, beer lover and fight fan, already in office, and he's just announced tax cuts."

"You think there's no contest?"

"I wish there were."

Clyde brought the tea, then left them alone. Breathing in warm scents from the kitchen, Josh watched as Suzanne brought the portable screen to life. Then she tapped her phone, and the unfurled screen showed a room interior, Suzanne sitting at an angle to Richard Broomhall. Josh put his own phone on the table; both handsets winked amber, establishing a shares.p.a.ce. In the image, she was putting young Richard at ease; in reality, she was tugging down her sleeve which had pulled up, just by centimetres.

Few people would have noticed; but Josh needed only a glimpse to take in the silver scarring.

"You want audio?" Suzanne took out her earbeads. "Or just transcription for now?"

Printed text her words in red, Richard's in white scrolled down a side pane.

"Hmm. Can we get rid of both for the moment?"

"All right."

"This will help the automated search." As he tapped his phone, dots sprinkled themselves across Richard's moving image, then lines joined the dots, like moving wire frames. "Improve the motion a.n.a.lysis."

"On CCTV, you mean? Like on the Tube?"

"Uh-huh. My bots can look for subtle things like see that? The way he rubbed his nose? If that's a habit, we've just increased our chances."

"Interesting." Her polished-chestnut eyes contained golden flecks. "Emphasising process over content. That's close to the way I work, because I'm as interested in his posture and voice tone as in the actual words."

"But if he'd said anything about where he might go, you would have picked it up. And the police have seen this?"

"Yes, so they should have picked up any local references I missed."

When she focused on him, it was like the total universe concentrating its attention; when she looked at the screen, she was absorbed in the images. To Josh, this was extraordinary.

"Here we are." Clyde bore plates of spicy bean stew with rice and bread. "Enjoy, enjoy."

"We will."

"Smells terrific," said Josh.

And the taste burst into his mouth, slowing him right down. Suzanne blanked the screen now it was the food she concentrated on and they made little conversation until their plates were mostly empty. She pushed her plate aside just moments before he finished too.

"I don't understand" he would have liked to enjoy the warm feeling a while longer, but they were here for a reason "what you mean by process over content. In your work, that is."

"Look at this interaction." She worked her phone, bringing the screen back to life and skipping to a timestamped moment. "Here, we're discussing Richard's reaction to blades."

The words scrolled down the transcript pane.

"See here?" Suzanne slowed the movie down. "That gesture with his left hand, cupped toward his stomach? An unconscious reaction to my question, in parallel to the words he spoke, telling its own story."

Josh frowned. "Gestures like that mean something?""Movement and timing are most important. Here, his left hand under control of his right cerebral hemisphere indicates he gets an automatic feeling in his stomach at the thought or sight of knives. It's an internal reaction, call it gut feeling, and it's real because every major organ has receptors for neuropeptides, almost like another nervous system."

"Really?"

"When people say something is heartfelt heartfelt, it's often more literal than they think. Figures of speech have to come from somewhere."

Josh had felt his guts roiling in circ.u.mstances most people would never know. Visceral feelings were intense; he knew they were real.

"So how does that help you?"

"Everything is mental modelling. Even a black shirt in the open air reflects less light than a white shirt indoors, so something as basic as colour is a neural process."

"Computation," he said.

"Exactly. By using Richard's imagination, I could have got him to focus on the fear-feeling, experience it as a loop... See, you haven't noticed the feeling of your sock on your left foot until I mentioned it, because a constant sensation just fades away. So a gut feeling doesn't literally keep looping around, but while it's strong it feels that way."

"All right." Josh was smiling, still aware of his foot.

"In his imagination, I could've got him to spin the feeling in the opposite way, add some visualisation, and his fear reaction would be gone. Sounds too simple to work, yet it does."

"But you didn't do that."

"No, look. I taught him something else, but not for blades specifically." She flicked through thumbnail stills, then jumped the main pane to another part of the session. "Here, Richard is imagining something, and see how his eyes focus on a point in s.p.a.ce? Even though he's seeing a picture in his mind? The entorhinal cortex has a component called the spatiotemporal grid which Well, I'll save the neurology lecture for later, shall I?"

"If you like." The idea of a later was appealing to Josh. "So what happened next?"

"I taught him to experience the picture differently. Push it off to a different location and imagine it flaring bright, then washing out."