'Ah,' Hazo said. 'Very clever.'

'Makes it very easy to track vehicle movements from the sky.' He casually moved to the next pickup and scrawled an invisible star on its hood. 'I've already got the serial numbers for all the military vehicles in Crawford's platoon. Those can be tracked in-house by our agency using GPS, no problem. If, however, one of these trucks goes missing, they fall off the grid. Unless they're marked.' Another glance to the camp, and Jason stepped up to the third pickup. This time, he traced out a square. On the hood of the fourth pickup, he drew an invisible triangle. Capping the marker, he slipped it back inside his pocket. Then he pointed to each pickup in turn, saying, 'Circle ... star ... square ... triangle.' He committed each pickup to memory - paint, model, distinguishing marks (like the blown-out windshield and blood-smeared cab of the pickup that had been the convoy's lead vehicle).

'Very good,' Hazo said, impressed.

'And since we're on the topic of satellites ...' Jason pulled out his binoculars, activated the infrared, and discreetly spied Crawford's position in the tent. The colonel was still on his call, pacing in small circles. 'Who are are you talking to, Crawford?' Jason muttered to himself. He used the laser to calculate Crawford's GPS grid. Then he flipped open his sat-com and put out a call of his own - one which Crawford certainly would not approve. you talking to, Crawford?' Jason muttered to himself. He used the laser to calculate Crawford's GPS grid. Then he flipped open his sat-com and put out a call of his own - one which Crawford certainly would not approve.

31.

'Mack, it's Yaeger. I need a big favour,' Jason said. Thanks to the cloudless Iraqi sky, the sat-com's reception was flawless. On the other end of the call, he could easily hear GSC's star Communications and Remote Weapons Specialist crunching away on some potato chips.

'Another favour?' Mack ribbed him. 'You're very needy lately. Dare I say clingy?'

More crunching.

'You sound like an angry girlfriend.'

'You wish you were so lucky.'

Now some slurping.

'You're not my type, big fella.'

'Yeah, I suppose. Too much back hair and you like 'em smooth. I get it. Anyway ... what can I do you for you this time? Fire some missiles up some Taliban's a.s.shole? Or do you need a Predator to deliver a care package to a Hezbollah Tupperware party? Name it. I'm yours.'

Scary thing was, Jason thought, the guy was willing and capable of either act. 'Nothing that dramatic.'

'Darn.'

'Just wanted to test your IQ on satellite phone communications. Put your NSA skills to the test.'

As with most of the firm's intellectual a.s.sets, Macgregor Evan Driscoll - MIT Summa c.u.m Laude graduate and part-time hacker - had been recruited from the Department of Defense's most obscure branches known only by obscenely long acronyms. In 2002, he'd been instrumental in helping the NSA design a covert listening station inside AT&T's San Francisco international telecommunications hub. The programme's focus had been to monitor phone chatter and e-mails originating from Al-Qaeda safe houses in places like Riyadh and Yemen. But a whistleblower outed the programme for spying on domestic communications as well, exposing a myriad const.i.tutional violations. This chapter of the Bush Administration's unwarranted wiretapping programme promptly folded and its developers, including Mack, became victims of the political fallout. But Mack was quickly scooped up by GSC - a firm that used a much different playbook and embraced the frustrated, cavalier brainiacs who'd been disenfranchised by the tight monetary and operational constraints of government agencies.

'What've you got for me?' Mack asked.

'I've got a guy here in Iraq who's been making lots of calls, with the intent of undermining our mission. If I give you his coordinates, can you see if you can listen in on him?'

'I'll give it a go.'

Jason twice repeated the GPS data for Crawford's current position. Then he heard Mack tapping away on a keyboard. He'd gone through this exercise many times in the past, so he knew Mack was linking in to the commercial satellite network to triangulate the signal.

'Hum. Got the signal ...' More tapping. 'Oh yeah, that's gonna be a problem. Your caller's not using a voice channel ... and he's transmitting in digital, not a.n.a.logue. And And it's all bouncing through military satellites. Nice if you would just say that you want me to eavesdrop on the marines.' it's all bouncing through military satellites. Nice if you would just say that you want me to eavesdrop on the marines.'

'Sorry about that,' Jason said. 'Can you crack the encryption?'

'Four-thousand-ninety-six-bit RSA secure-key encryption?' Mack cackled. 'Don't think so. That s.h.i.t was invented because because of guys like me. The number of possible key combinations borders on infinity. Would take decades for the world's fastest supercomputers to crack that kind of encryption.' of guys like me. The number of possible key combinations borders on infinity. Would take decades for the world's fastest supercomputers to crack that kind of encryption.'

'All right,' Jason said. There had to be another way. 'So the caller and the person being called each have a key cipher, right?'

'That's right. Both phones use the same key encryption software to swap permissions.'

Jason thought it through. Two keys. Two sources. Encoded data packets being fed back and forth between two points with an ultra-tight digital handshake. Maybe he was approaching the problem from the wrong angle. 'How about this: can you locate the second key?'

'Yeah, sure,' Mack replied matter-of-factly. 'May not do you any good if the person on the other end is mobile. 'Cause once this call's over, it's a whole new ball game. New keys, new session-'

'Humour me, Mack.'

'All right.'

Jason listened to fifteen seconds of click-clacking accompanied by Mack's heavy breathing.

'Well h.e.l.l-o-o-o-o h.e.l.l-o-o-o-o ...' Mack sang in pleased revelation. 'You just got very lucky, Yaeger.' ...' Mack sang in pleased revelation. 'You just got very lucky, Yaeger.'

'How's that?'

'This call's being routed through a ground station in San Francisco. Jeez, it's going through AT&T at Folsom Street. Same place I used to work ...That's f.u.c.kin' rich ...' he said with some resentment. 'Anyway, the satellite feed is routing through the Backbone network.'

'So whoever he's talking to is not using a mobile phone?'

'Tell you in a second.' Mack did some more tracing. 'Nope. Definitely a landline. Still can't tell you what they're talking about. But I can tell you exactly where the other caller's phone is plugged into a wall jack.'

'That would be great.'

Now Mack was humming the Jeopardy! Jeopardy! theme song to the rhythmic keyboard clicks. 'And ... got it.' A pause. 'Huh. I think your guy might be calling his bookie.' theme song to the rhythmic keyboard clicks. 'And ... got it.' A pause. 'Huh. I think your guy might be calling his bookie.'

'Come again?'

'Yeah, your marine is talking to someone in Vegas.'

'Las Vegas? You sure about that?' You sure about that?'

'Yup. And it gets even weirder. Seems his bookie is an evangelist.'

32.

BOSTON.

Only minutes ago, Agent Thomas Flaherty and Professor Brooke Thompson had arrived at the branch office of Global Security Corporation. Sipping tea from a Styrofoam cup, Brooke sat alone in Flaherty's spartan cubicle, peering out the east-facing window that provided a spectacular tenth-floor view of downtown Boston. Directly below was Quincy Market, where the city's historic colonial centrepiece, Faneuil Hall, sat dwarfed beneath the sleek skysc.r.a.pers of the financial district - a sharp juxtaposition of America's past and present. Her gaze panned out beyond the Christopher Columbus waterfront park and the Long Wharf promenade to settle on Boston's Inner Harbor. Shafts of sunlight lanced the grey clouds and joined in a sparkling circle atop the icy dark water. Maybe, she hoped, the bright spot portended more than just a pa.s.sing storm.

The past half-hour had been a whirlwind. Following the harrowing escape in the tunnel, Flaherty had exited the Ma.s.s Pike and continued on to downtown. His wrecked car was ignored by the police cruisers, which sped past in response to the fatal collision blocking the interstate tunnel deep beneath Copley Place. At this moment, she thought, another Big Dig was currently under way.

She was still struggling to reconcile how Flaherty had so brazenly put their lives on the line, though he had done an adequate job of explaining to her that a.s.sa.s.sins were incredibly driven to finish their work. 'Those guys are hardwired to do whatever it takes to eliminate their targets,' Flaherty had told her. 'Failure to do so means the end of an a.s.sa.s.sin's career, and possibly his own life. Gives them a pretty powerful incentive to win.'

Flaherty had also told her that he'd been trained to avoid at all costs getting into a shooting match with hired guns, since most were former marine snipers and Special Ops commandos. So the prudent course of action was simple: flee. And, miraculously, Flaherty had managed to do just that.

The a.s.sa.s.sin's failed attempt would take time to disseminate back to the unknown client, Flaherty had told her. And that precious time 'off the grid' provided them a fleeting tactical advantage.

It was no wonder that he'd headed directly here, she thought, turning her attention back to where she was. This seemingly innocent office was a veritable fortress that would be near impossible for an outsider to infiltrate. At the entrance to the building's parking garage, Flaherty had been required to present his encrypted security badge to a trio of heavily armed, burly security guards wearing crisp navy coveralls with red arm bands and GSC shoulder patches (the agency's patriotic emblem purposely designed to convey a symbiotic relationship to the US military). The head guard had quizzed Flaherty about the Concorde's alarming condition, while one of his minions performed a cursory search of the car's interior and trunk.

Meanwhile, the third guard had requested for Brooke to step out from the vehicle so he could wave a security wand over her limbs and torso. Then he'd brought her to a computer terminal and vetted her while running a check on her driver's licence. Satisfied that she harboured no propensity for espionage, he had escorted her back to the Concorde and held open her door in polite valet fashion.

After the head guard had let down the retracting thick metal posts that blocked the garage's entrance ramp, Flaherty had driven on to his reserved ground-level parking spot. He'd used the same ID as a keycard to access a dedicated elevator that had no control panel, only an emergency stop b.u.t.ton and panic phone, and a security camera. The elevator had let them out directly into an elegant entry foyer, furnished with plush leather armchairs, oak-panelled walls, flat-screen televisions tuned to MSNBC, CNN and Fox, and a receptionist seated behind a sliding gla.s.s window. At first, Brooke had felt like she'd stepped into her dentist's office. But the main entryway, situated at the end of a short corridor leading off the reception area, was fitted with a formidable security door. With two more armed guards flanking the door, it was anything but welcoming.

The facility itself took up the building's entire tenth floor, with a 'team-based' open-plan office that provided clear views to windows on all four sides. When Brooke had commented to Flaherty on the irony of all this security for an office surrounded by gla.s.s, Flaherty had explained that the windows were blast-proof, tinted to keep out prying eyes both day and night, even dampered against vibration to prevent hi-tech spies from tracing conversations with parabolic microphones. 'This ain't no fish-bowl,' he'd conspiratorially confided.

No matter what work was performed here (or at the firm's twenty-six similar offices Flaherty had said were located around the globe to ensure maximum redundancy and logistical advantages), the layered security protocols seemed excessive. She figured the firm was a living testimonial to its products and services.

But even this hi-tech nerve centre had no knowledge of why Brooke Thompson had been secreted into Iraq in 2003, and why now someone wanted her dead because of it.

G.o.d, how can this be happening?

33.

'Brooke,' a voice suddenly squawked over the intercom on the desk phone.

'Yes?' Brooke spoke quietly into the phone.

'It's me. Flaherty. Stand up.'

'What?'

'Just do it.'

She did.

'Look to your left. See me over here?'

Directing her gaze left, she saw a hand waving to her. Flaherty's head popped up over the cubicles. She waved back at him.

'Come on over here,' he said, before disconnecting.

Noting his position, Brooke set off through the part.i.tions.

Angling her way through a maze of office cubicles, Brooke snuck glances at Global Security Corporation's resident employees - mostly attractive twenty-something males and females wearing business casual attire and slim headsets. Each techie monitored not one, but three to five flat screens packed with streaming data.

Nearer where Flaherty stood at the centre of the floor, the hi-tech workstations were laid out along a wide semicircle. Here the computer displays were dominated by tactical maps and schematic blueprints.

'Come on over, Brooke,' he said, waving her closer. 'There's someone I'd like you to meet.'

The person to whom Flaherty was referring stood from her chair. Barely reaching the agent's shoulder, the pet.i.te woman had bobbed grey hair and wore a tasteful flannel pants suit.

'Annie is our resident expert on satellite surveillance. Our eye in the sky.'

'Hi, Brooke. A pleasure to meet you,' Annie said.

Brooke immediately pegged Annie's refined New England accent, heard so many times at university charity events and museum fundraisers. It sang of old money. Annie proffered a dainty, manicured hand that hosted a jaw-dropping emerald-cut diamond ring that validated Brooke's a.s.sessment.

'Thanks. Nice to meet you too,' Brooke replied warmly.

'Tommy's told me you've had quite a crazy day.'

Brooke rolled her eyes and sighed. 'It's like a bad movie.'

'You poor dear,' Annie said, smiling sympathetically.

'Brooke, I want you to take a look at this,' Flaherty said, pointing to the images on the display that they'd been reviewing. 'Have a seat.'

Easing into the chair, Brooke stared at the monitor, which showed an incredibly detailed aerial shot of a highly diverse terrain. The software interface looked like the next generation of Google Earth. There were mountains to the top and right of the screen, green flatlands in the middle and to the left, and brownish tans blending in at the bottom. Roadways appeared as thin lines, and webbed throughout the land to connect a disparate matrix of dense cities. Though for Brooke, the rivers snaking through the plains were the region's true fingerprint.

'Just want you to confirm something for us,' Flaherty said. 'We're looking at-'

'Northern Iraq,' she said.

Annie smiled. 'Right.'

Brooke antic.i.p.ated Flaherty's request. 'The cave was right here, in the mountains.' She pointed to the exact spot. 'There.' She looked up at Flaherty. 'Did I pa.s.s the test?'

He smiled. 'Yup.'

Annie leaned in to get a closer look. 'That's it,' she confirmed.

'With the eight-hour time difference, it's nighttime there right now,' Flaherty said. 'So this isn't a live shot. It was taken earlier today. But you'll get the idea.'

Annie pulled up a chair, sat beside Brooke, and used the mouse to steadily zoom in on the Zagros Mountains. As the eye in the sky homed in on the military encampment set at the bottom of a hill, Brooke felt like she'd been transported back in time. Gooseb.u.mps p.r.i.c.kled her arms.

Bending over Brooke's shoulder, Flaherty used a pen as a pointer. 'A few hours ago, our deep-cover field agents ambushed four trucks on the roadway here,' he said, pointing to the winding gravel ribbon running along the bottom of the screen.

Brooke could see bodies littering the ground around what looked like four pickup trucks left askew in the roadway. 'G.o.d,' she gasped. 'Are those men dead?'

'Oh yeah,' he said. 'But trust me, they deserved it.'