Gambetta beamed, a vain attempt to pull his stomach in and push his chest out making his face flush.

‘Do you mind if I have a quick look through the rest of Cavalli’s stuff?’

‘Of course not. Here, I’ll move it over there where you can see properly.’ He scooped the box up and led her a short way further down the aisle to where a battered angle-poise lamp decorated with the small stickers found on imported fruit had been arranged on a folding table. ‘That’s better.’

‘Much,’ she smiled. ‘You’ve been incredibly -’

There was a rap against the counter window at the far end of the room. Gambetta placed his fingers against his lips.

‘Wait here,’ he whispered conspiratorially. ‘I’ll get rid of them.’

He lumbered back towards the entrance, leaving Allegra to go through the rest of the contents of the box. Much of it was what you’d expect to find in someone’s pockets: a mobile phone – no longer working – some loose change, reading glasses, a damp box of matches and an empty pack of Marlboro Lights. His wallet, meanwhile, as loaded with the standard everyman paraphernalia of cash, bank cards, identity card and an assortment of disintegrating restaurant receipts.

There was a nice watch too – round and simple with a white face, elegant black Roman numerals and a scrolling date. Unusually, apart from the Greek letter Gamma engraved on the back of the stainless steel case, it seemed to have no make or logo marked anywhere on it, featuring instead a distinctive bright orange second hand which stood out against the muted background. Finally there was a set of keys – house and car, judging from the Maserati key fob.

An angry shout made her glance up towards the entrance. Gambetta seemed to be having an argument with the person on the other side of the window, his voice echoing towards her. As she watched, he stepped away from the window, unclipped his keys from his belt, and waved at her to get back.

Allegra didn’t have to be told what to do. Still clutching Cavalli’s keys, she retreated to the far end of the aisle and hid. Gambetta had done her a favour by letting her in here and the last thing she wanted to do was get him in trouble. Even so, she couldn’t quite resist peering around the edge of the pier as he unbolted the door.

She never even saw the gun, the rolling echo of the shot’s silenced thump breaking over her like a wave before she’d even realised what was happening. The next thing she knew, Gambetta was staggering back, his arms flailing at his throat, legs buckling like an elephant caught in a poacher’s snare. He swayed unsteadily for a few moments longer, desperately trying to stay on his feet. Then, with a bellow, he crashed to the concrete floor.

J. Edgar Hoover Building, FBI headquarters, Washington DC

18th March – 10.37 a.m.

The fifth floor was much busier than the one he had just come from. Even so, Tom wasn’t worried about being recognised. Of the eight thousand or so people who worked out of this building, he doubted whether any more than five knew who he was. And rather than hinder him, the floor’s bustling, largely open-plan configuration made it easier for him to blend in and move around unchallenged.

What was immediately clear, however, was that here, news of what had happened last night in Vegas had already spread. There was a strained atmosphere, people going about their usual business with a forced normality, judging from their sombre faces and the irritable edge to their voices. Tom, it seemed, wasn’t the only one who was finding comfort in anger’s rough-hewn arms. And yet, amidst the bitterness, he detected something else in people’s eyes, something unsaid but no less powerfully felt. Relief. Relief that it hadn’t been them. He wondered how many people had called up their wives or boyfriends or children this morning upon hearing what had happened, just to hear the sound of their voice. Just to let them know that they were okay.

As the operator had suggested, Tom found the room Jennifer had been camping out in the northeastern quadrant of the building. Like all the other offices that lined the perimeter of the floor, it was essentially a glass box, albeit one with a view of 9th Street and a nameplate denoting the identity of its rightful owner – Phil Tucker. Unlike the rooms which flanked it, however, its door was shut and all the blinds drawn in what Tom assumed was a subtle and yet deliberately symbolic mark of respect. Less clear was whether this was a spontaneous reaction to Jennifer’s death or part of some well-defined and yet unwritten mourning ritual that was observed whenever a colleague fell in the line of duty. Either way, it suited him well, concealing him from view once he had satisfied himself that no one was watching him and slipped inside.

Almost immediately, Tom’s heart sank. Perhaps without realising it until now, he had secretly been hoping to find a bit more of Jennifer here, even though he knew that this had only ever been a very recent and temporary home for her. Instead it boasted a sterile anonymity that was only partly lifted by Tucker’s scattered photographs and random personal trinkets. Then again, he couldn’t help but wonder if Jennifer’s hand wasn’t perhaps present in the clinical symmetry of the pens laid out on the desktop and the ordered stack of files and papers on the bookshelf, that he suspected had probably been littering the floor when she had first taken ownership of the room. And there was no debating who was responsible for the lipstick-smeared rim of the polystyrene cup that was still nestling in the trash. He gave a rueful smile. She had been here, after all. He was a guest, not an intruder.

The safe was in a cupboard under the bookshelf. With a weary sigh, he saw that it was protected by both a password and voicerecognition software, two red lights glowing ominously over the small input screen. Tricky. Very tricky, unless…He glanced up at her desk hopefully. The light on her phone was glowing red to indicate that somebody had left her a voicemail. With any luck, that also meant that she’d recorded a greeting.

He picked the phone up and dialled Jennifer’s extension, the second line beeping furiously until it tripped over into the voicemail system.

‘You’ve reached Special Agent Jennifer Browne in the FBI’s Art Crime Team…’ Tom’s stomach flipped over at the sound of her voice, as if he’d just gone over a sharp hump in the road. She sounded so close, so real that for a moment it was almost as if…It was no use, he knew. This was an illusion that would dissolve the moment he tried to warp his arms around it. He needed to stay focused. ‘Please leave a message…’

He replaced the handset. That would do. Now for the password. He bent down and opened each of the desk drawers, guessing that the lipstick on the cup was a sign that Jennifer, for all her refusal to play conventional sexual politics at work, had still occasionally worn make-up. He was right. The third drawer down yielded a small make-up bag and within that, a powder brush.

Kneeling next to the safe, he gently dusted the brush over the keys and then carefully blew away the excess. The result certainly wasn’t good enough to lift prints from, but it did allow him to see which keys had been most recently and heavily used, the powder sticking more thickly to the sweat left there.

Reading from left to right, this highlighted the letters A, C, R, V, G, I and O. Tom jotted them down in a circle on a piece of paper, knowing that they formed an anagram of some other word, although there was no way of telling how many times each letter had been used. The key was to try and get inside Jennifer’s head. She would have chosen something current, something relevant to what she had been working on. A name, a place, a person…Tom smiled, seeing that the last three letters had given him an obvious clue. G, I, O – Caravaggio, perhaps? He typed the word in and one of the two lights flashed green.