"He moved," Keiran explains. "I set the scanner to wake me up if the phone left the hotel grounds. He's just down the street. Get up, come on, go!"

Ninety seconds later Danielle and Jayalitha, clad in sandals and pyjamas, are jogging down the hallway to the elevator bank. Danielle holds one of their anonymous cell phones. She does not quite believe that she is really awake. Except that dreams are never this uncomfortable; being shaken awake this early was almost physically painful.

"Remind me again why you can't come with us," she says into the phone, annoyed. "Just in case someone sees your precious face?"

"Believe me, I want to be there. But I have to stay here to monitor his activity and make the finger call. Let me know when."

There is more activity on the street outside the Alexis Park than Danielle would have expected at four in the morning, even in Las Vegas. At least fifty people cluster, smoking and talking, around the 24-hour 7-11 store down the street, at the corner of Harmon and Paradise. A group of a half-dozen passes them on the way to the store. From their chatter Danielle gathers that a big party has just ended; from their giggles, shining eyes, and the way they gape at street lights, it's clear hallucinogens were involved. Two other groups pass them going back into the hotel. Their members seem very young. Danielle supposes old fogeys like herself, even those who took drugs, are mostly in bed by now. As she would very much like to be. She doesn't know if she can pick out a single person answering a phone in this noisy, milling crowd, but she doesn't know if they'll get a better chance, either. She decides to go for it and opens her mouth to tell Keiran so.

"Bollocks," Keiran says. "He's back inside. He must have walked right past you."

"Why the fuck didn't you tell us?" Danielle demands, turning around.

"It's not a real-time scan. Every thirty seconds."

The two groups who passed them looked college-age, if that. Danielle wonders if their fearsome nemesis P2 will turn out to be a pimply monomaniacal teenager. Both groups continue, their pace leisurely, through the main building and down the long outdoor walkway that winds past the Alexis Park's three swimming pools. Danielle and Jayalitha follow.

"He stopped," Keiran reports, a minute later.

Danielle shakes her head. "The people who passed us are still moving."

"Then he's not with them. Or not any more. Where are you?"

"By the main pool."

"Go back. Check the lobby."

They return indoors. There are eleven people on the lobby chairs and couches; one group of four teenage boys, two couples, and three lone men, one reading a newspaper and two more working on their laptops. She reports this to Keiran.

"All right," Keiran says. She hears him take a deep breath. "He has to be there. The phone might be silent. Keep a sharp eye. I'm going to connect."

"He's doing it," Danielle whispers to Jayalitha, who nods.

"Well?" Keiran asks, fifteen seconds later.

"Did you do it?"

"Yes. It rang. Someone answered. They didn't speak. I started talking and they hung up, they must have some code-word system. You didn't fucking see anything?" The frustration in his voice is palpable.

"No. They're not here."

"Danielle," Jayalitha says. "The lavatories."

Danielle turns and looks at the two doors, marked with the universal man and woman symbols, set in wood panelling. Of course. P2 stopped in to take a leak on his way to the pools.

"Come on," she says, and she and Jayalitha barge into the men's room.

There is a man standing by the sink, young and pot-bellied, with wide Elvis sideburns. He looks at them with surprise and alarm.

"P2, I presume?" Danielle asks.

His surprise and alarm intensify. "Huh?"

Jayalitha pushes past Danielle, grabs the man by his lapels, and pulls him down to her height.

"Are you P2? Do you work for Shadbold? For Justice International?" Her voice is low but throbbing. "Answer me."

"What the fuck you on, lady?" The man tries to separate Jayalitha's hands from his clothing. The attempt earns him a kneecap hard in the crotch. He doubles over, hands folded over his battered genitals. Soft gagging noises come from his mouth.

"If you move," Jayalitha warns him, "I will end your miserable life." She crouches to the collapsed form. "And if you are the one I seek I swear to you, you will burn just as my family burned." She pulls a cell phone from his pocket and gives it to Danielle.

Danielle stares at Jayalitha for a moment. It is like seeing a kitten turn into a wolverine. Then, as the man writhes in gasping agony, and Jayalitha searches him thoroughly for any other, hidden phone, she turns her attention to his phone. It is a Nokia, she knows its interface well. She quickly establishes that it last received a call more than an hour ago.

"No," Danielle says. "Not this one."

Jayalitha looks up, past the urinals, to the stalls. One of the doors is closed.

"It is occupied," she says. "You must knock down the door. I will keep this man from leaving."

Danielle swallows. The situation is both absurd and appalling. But they have done too much to back out now. And besides, she reminds herself, she is already wanted by the FBI. She walks up to the stall. She hears fast, shallow breathing from behind it. Its occupant is afraid.

"Open the door," she says.

"What the fuck is this?" A frightened, teenage voice.

Danielle considers kicking the door, but decides that sandal-clad feet are not right for this. There is enough space beneath the stall door and walls that she could wriggle in, but she would leave herself vulnerable to physical repulsion, and it would be somehow undignified. There are no tools in sight; she will have to do it herself. She feels blood pounding in her temples.

"You do not move except to breathe!" she hears Jayalitha warn the man on the floor, her voice still harsh, as if he might yet turn into P2. He whimpers an understanding.

Danielle steps back to the wall, crouches, tenses her abdominal muscles, and charges the stall shoulder-first. It pops open with surprising ease. She very nearly falls into the gangly teenager sitting on the toilet within, wearing shorts and a T-shirt. Something metal, the stall lock, rattles on the floor.

"Are you P2?" she asks, feeling ridiculous. At least he has already drawn up his shorts in anticipation of her invasion.

"I don't know what you're talking about." His voice quavers.

"Give me your phone."

He pauses for a moment. Then another thump and groan of pain from near the door. The other man must have tried to make a move. The teenager quickly draws his phone out and passes it over. It too has not been used within the last hour. He can't be hiding any other phone in his shorts, unless –

"Stand up and drop your pants," Danielle orders. When she hears the words leave her mouth she very nearly starts giggling like a madwoman, and stops this only by biting her lip so hard she tastes blood.

The teenager stares at her. Then, slowly, he stands up and lowers his shorts. There is no cell phone concealed within. Perhaps it was flushed away? – but no, a quick glance reveals that the toilet has not been flushed, and no phone gleams within.

"Stay where you are," Danielle commands. She drops the phone, kicks it to the far corner of the bathroom, walks back to the doorway, takes Jayalitha by the wrist, and leads her out into the lobby, just as a teenage blonde girl comes out of the women's room, babbling at high speed into her cell phone: "And then she was all, like, Christina's a totally better singer than Britney, and I was like, duh, totally, everyone knows that, but it's not about the voice, it's about, like, the style." She stops and looks at Danielle and Jayalitha. "Uh, excuse me, ladies, I think you want this door, unless you're, like, totally desperate for male companionship." She points at the women's room and smiles archly.

"We're fine," Danielle says shortly, humiliated enough already without this bubbleheaded ditz adding to it, and marches out of the main building, towards the pools and their room, before the men they have left behind come to their senses and raise a furor. Her face is red, and she feels weak, from confrontation comedown, embarrassment, and a sick sense of disaster. They should have found him. They failed. And now he must know he is being traced.

They are just past the main swimming pool when Jayalitha grabs Danielle's arm from behind and pulls her her to a stop.

"What is it?" Danielle asks.

"The other room. The ladies' room." Jayalitha turns and rushes back to the lobby.

"That ladies' room? But why would he..." Danielle says, following, and then she understands.

He. That has always been their assumption. But they have no reason other than demographics to believe P2 a man. And P2 is, by all accounts, a truly exceptional hacker; and true exceptions are beyond statistics.

The men's room opens as they approach. The two men they terrorized look out nervously, blanch at the approach of Danielle and Jayalitha, and quickly shut the door again. They proceed into the women's room. It is empty.

"The girl," Danielle says. She can't believe it. The teenage blonde girl with her overdone white-trash-pop-culture spiel. She rushes out into the lobby. She is nowhere to be seen. But Danielle is sure. Dead certain. Something in the look the blonde girl gave them when she pointed at the women's room. A hint of triumph.

P2 is a teenage girl. And she knows their faces. And knows she is being chased.

** *

"Well," Keiran says. "This is not good."

"We know that," Danielle says grimly.

"But it's not a total catastrophe. We had one piece of information. It's now useless, that phone's been switched off. And they'll be looking for us here now. That's bad too. But you did add to our store of knowledge."

"How?" Jayalitha asks.

"You know what she looks like."

That is true. Danielle tries to remember. Short, dirty blonde hair, probably natural, cut a little above her shoulders. Upturned nose, wide mouth, good skin, no jewellery. Maybe ten pounds over her optimum weight. She was wearing hiphugger jeans, a tank top, and sandals.

"The human brain is an amazing pattern recognition machine," Keiran says. "When it recognizes a face it does in a fraction of a second what computers require hours to manage."

"Yes. We can recognize her. But she's not going to be parading around the hotel any more, is she?" Danielle asks, exasperated.

"Never mind the future. We have the past."

Danielle looks at him, irritated by his typically cryptic comment, and then guessing its meaning. "Cameras. The hotel has cameras. You can take them over."

"Unfortunately, no. This is, after all, DefCon. The hotel cameras get pre-hacked weeks in advance. It scores major bragging rights. I don't know who owns them right now, but we probably can't risk asking them for a favour. But I do happen to know that our friends at 7-11 have moved to a central webcam security system in all their stores, so they can document hold-ups and shoplifting across the whole chain. And you know what that means."

"Shazam to the rescue?"

"With luck. You two can get back to sleep. This will take me an hour or two." He sounds eager.

"I'll wake you when I've got something."

"That's big of you."

"Oh, and don't forget, don't go out. Either of you. She saw you too."

"What if she took over the hotel cameras?" Jayalitha asks.

"Then we're fucked. Sweet dreams."

** *

This time Danielle wakes to the smell of bacon and eggs. It is nine A.M.

"I room-serviced breakfast," Keiran says absently, as Danielle pokes her head into his room to see what is happening. "Help yourself. I won't be a moment with this. I'm in their network like a snake in the plumbing." But both Jayalitha and Danielle have showered, their breakfasts are devoured, and their mugs of tea are almost empty, before Keiran finally grunts with triumph.

"Who would have thought 7-11 would have been such a nut to crack?" he demands cheerfully. "If their head office hadn't been Shazam-crazy I never could have done it. No matter. Here's the video from across the street, from ten minutes before you left the hotel. Sing out when you see her."

Danielle and Jayalitha peer at the slightly grainy footage. She isn't there. They watch intently, as if Late Night 7-11 Camera was the most fascinating reality TV show ever, as customers line up and pay for for cigarettes, chocolate bars, and Slurpees.

"There!" Jayalitha exclaims. Danielle echoes her. They watch P2 come through the door of the store, glance up directly at the camera for a moment, and then proceed to the counter, where she buys a pack of Marlboro Lights.

"I love that look at the camera," Keiran says with satisfaction. "Classic hacker instinct. Betrayed you this time, sweetheart, didn't it?"

"Betrayed her how exactly?" Danielle asks.

"Hopefully," Keiran admits. "This is conjecture. But think of it this way. You're P2. You come here for perfectly innocent reasons, to check in on the state of the hacking art, and then you find out that the dastardly fugitives your friends in LA were supposed to track down are here looking for you. And you're presumably rather annoyed by this turn of events. What do you do?"

"Get out of town," Danielle says.

"No," Jayalitha corrects. "I would call for assistance to deal with the dastardly fugitives. I would stay in the city. But I would move to another hotel."

Keiran nods. "My guess exactly. And at some point, when you check into that other hotel, you will pass a cashpoint or step into an elevator. And you know what that means."

"We can't sit here looking at all the cameras in Las Vegas," Danielle objects. "It would take our whole lives to find her."

"Quite true. This job cries out for automation. Something like a powerful facial recognition program. I think I can dig at least two of those up on short notice. The one Klaupactus wrote is probably the best. It requires front and side views of the target's face, but conveniently we now have just that."

"You were just saying that computers take hours to recognize a face," Danielle points out.

"Yes. And that's why they'll never imagine I can possibly do what I am about to do. Because they don't know that I have at my disposal the most powerful accumulation of computing power ever assembled on the planet."

"Excuse me?"

"Shazam," Keiran says. "Seven million instances, remember. All of them at my beck and call. And this is just the kind of granular problem you can go massively parallel on. With seven million computers working on this problem, it'll be like every camera in Las Vegas is looking for our little blonde sweetheart and knows how to shout out to us if she walks by." He sighs. "It's a blatant violation of LoTek's Law, of course. I wrote the parallel processing code hoping I'd never have to use it. It will probably be Shazam's final blaze of glory. Seven million computer owners will start wondering what just happened to their suddenly very slow machines. Backbone administrators will start asking why global Internet traffic just spiked twenty per cent. But better that than some real-life Gil Grissom trying to work out what happened after our corpses are found out in the desert."

"What if she left town after all?" Danielle asks.

Keiran nods. "Then I'll have burned Shazam for nothing. It's a gamble. But what the hell We're in Vegas. Let's roll the dice. Give me space, if you would. Operation Argus has now begun."

Eight hours later, a beaming Keiran shows them footage of P2 checking into room 1723 of the Mirage. According to the Mirage's records, her name is Sophia Ward, and she is nineteen years old.

"Come on," he says. "Let's go have a little chat with our angel of cyberspace."