Reaching the phone down from the desk, he listened to Jennifer’s greeting a few more times to get a feel for the timing of exactly when she said her name. Then, just at the right moment, he placed the handset against the microphone before quickly snatching it away again. The second light flashed green. With a whir, the door sprang open.

He reached inside and pulled out a handful of files and a stack of surveillance DVDs. Returning the discs to the safe, he flicked through the files, discarding them all apart from one that Jennifer had initialled in her characteristically slanting hand.

Sitting at the desk, he unsealed the file and scanned through it, quickly recognising in the typed pages and photographs the details of the case that Jennifer had laid out for him on their way to Vegas. The anonymous Customs tip-off. The discovery of the Eileen Gray furniture hidden in the container. The tracing of the container to a warehouse in Queen’s. The raid on the warehouse and the discovery of an Aladdin’s cave of illegally exported antiquities. The panic-stricken dealer’s stumbling confession. A copy of his doodled sketch of the two snakes wrapped around a clenched fist, the symbol of the so-called Delian League that the forensic lab had reconstituted from strips of yellow paper recovered from his shredding bin. Bank statements. An auction catalogue. And, of course, the name provided by the dealer which Jennifer had passed on to the Italian authorities who had rewarded her with an address in Rome and a promise to follow-up: Luca Cavalli, Vicolo de Panieri, Travestere. It wasn’t much, but it was a start.

Closing the file with a satisfied smile he stood up, only to brush against the mouse as he turned to leave. The log-on screen immediately flickered on, the cursor flashing tauntingly at him. He stared at it for a few moments and then, shrugging, sat down again. It was worth a try.

Headquarters of the Guarda di Finanza, Viale XXI Aprile, Rome

18th March – 4.41 p.m.

Allegra snatched her head back, heart thudding, fist clenched, the teeth of Cavalli’s keys biting into her palm. Gambetta shot. No, executed. Executed here, right in front of her, in the basement of the Guarda di Finanza headquarters. It was ridiculous. It was impossible. And yet she’d seen it. She’d seen it and she only had to close her eyes to see it all over again.

Now wasn’t the time to panic, she knew. She needed to stay calm, think through her options. Not that she had many, beyond staying exactly where she was. Not with her gun stranded on the edge of Gambetta’s desk and only the length of the room separating her from the killer. Perhaps if she was quiet, she reasoned, he wouldn’t even realise…

The sudden hiss of polyester on concrete interrupted her skittering thoughts. She frowned, at first unable to place the noise, until with a sickening lurch of her stomach she realised that it was the sound of Gambetta’s corpse being dragged towards her.

She knew immediately what she had to do. Move. Move now while she still could; while the killer was still far enough away not to see or hear her. In a way, he’d made things easier for her. Now all she had to do was figure out which aisle he was coming down. As soon as she knew that, she’d be able to creep back to the entrance up one of the other ones. At least, that was the idea.

She shut her eyes and concentrated on the noise of the fabric of Gambetta’s uniform catching on the tiny imperfections in the concrete, fighting her instinct to run as the ticktock of the killer’s breathing got closer and closer, knowing that she had to be absolutely sure. Then, when it seemed that he must be almost on top of her, she opened them again. The second aisle. She was sure of it. The one she’d been standing in a few moments before when looking through Cavalli’s evidence box.

Taking a deep breath, she edged her head around the pier and peeked along the first aisle. It was empty. Her eyes briefly fluttered shut with relief. Then, crouching down, she slipped her shoes off and began to creep towards the exit, her stockinged feet sliding silkily across the cold floor. But she’d scarcely gone ten yards before suddenly, almost involuntarily, she paused.

She could see the killer.

Not his face, of course, but his back; through a narrow gap between the shelves as he dragged Gambetta towards her. Maybe if she…? No, she dismissed the thought almost as soon as it had occurred to her. It was stupid; she needed to get out of here while she still could. But then again, she couldn’t help herself thinking, what if someone here was working with him? It would certainly explain how he had got in. What if they now helped him escape in the confusion once she raised the alarm? She couldn’t risk that, not after what he’d done. A glimpse of his face, that was all she needed. Just enough to be able to give a description, if it came to that. If she was careful and stayed out of the light, he wouldn’t even know she was there.

Her mind made up, she edged carefully forward, trying to find a place where she could stand up without being seen, occasionally seeing the blur of the killer’s leg and his black shoes through cracks in the shelving as he backed towards her. Then, without warning, when he was almost parallel to her, Gambetta’s feet fell to the floor with an echoing thud.

Sensing her chance, she slowly straightened up, occasional gaps and openings between the shelves giving her first a glimpse of a belt, then the arrow tip of a tie, followed by the buttons of his jacket and finally the starched whiteness of his collar and the soft pallor of his throat. Through a narrow slit between two boxes.

There. She could see his face, or rather the outline of it, the overhead neon tube having blinked off yet again. Holding her breath, she waited until, with a clinking noise, the light stuttered on again, the image strobing briefly across her retina until it finally settled.

It was Gallo.

She instinctively snatched her head back, but the sudden blur of movement must have caught his eye because he called out angrily.

There was no time to think. No time to do anything. Except run. Run to the door, throw the bolts back, tumble through it, stumble up the steps and stagger out into the street, gasping with shock.

The world on its head.

J. Edgar Hoover Building,FBI headquarters, Washington DC 18th March-10.47 a.m.

Tom had found Jennifer’s password taped to the underside of the stapler. No great mystery there. It was always the same in these large organisations. Obsessed by security, IT insisted on people using ‘strong’ passwords that had to be changed every five minutes, and then claimed to be surprised when people chose to write them down. What else did they expect when most people struggled to remember their wedding anniversary, let alone a randomly assigned and ever-changing tencharacter alphanumeric code. The government was the worst offender of all.

He typed the password in and hit the enter key. Almost immediately the screen went blue. Then it sounded a long, strident beep. Finally it flashed up an ominously bland error message.

User ID and password not recognised. Please remain at your desk and an IT security representative will be with you shortly.

The phone started to ring. Tom checked the display and saw that it was Stokes, presumably tipped off by some clever piece of software that someone was trying to access Jennifer’s account. The Bureau was clearly more nimble and joined up than Tom had given them credit for earlier.

Shoving the file under his jacket, he leapt across to the door and, gingerly lifting the blind, looked outside. To his relief, everything seemed normal, the people working in the open-plan team room on the other side of the corridor still gazing into their screens or talking on the phone. Checking that no one was coming, he slipped out of the office and headed back towards the stairs and swiped the door open.