‘Not here, for Chrissake,’ Stokes yelled. ‘Are you fucking crazy? You’ll hit someone.’

Tom angrily shook him off, took aim and fired. The gun clicked, empty. With a wink, the killer turned and dived into the frothing sea of people.

In an instant, he was gone.

18th March – 12.23 a.m.

‘Where’s the backup? They need to set up a perimeter,’ Tom ordered angrily.

‘It’s a little late for that,’ Stokes shrugged helplessly at the untamed mob that had already spilled out on to the Strip, bringing the traffic to a standstill as they surged across the road, trying to get as far away from the Amalfi as they could.

Tom glared resentfully at the crowd, wanting Stokes to be wrong but knowing he wasn’t. What made it worse was that the gunman had played him. He’d seen Tom was carrying a Beretta, counted the shots until he’d known it was empty, then waited for him. Taunted him.

With a violent jolt, Tom’s thoughts snapped back to Jennifer.

‘How is she?’

‘The paramedics are with her now,’ Stokes reassured him, before lowering his gaze. ‘She’s lost a lot of blood.’

‘Where is she?’

‘They’re taking her up on to the roof for a medevac to UMC.’

‘Get me up there,’ Tom barked.

They ran back into the casino and, using the card Tom had taken from the security guard, rode up to the top floor.

‘What happened to the priest?’ Tom asked as the levels pinged past.

‘We lost him too,’ Stokes admitted. ‘Soon as everyone started running, he vanished. The money’s safe, though.’

‘You think I give a shit about the money?’ Tom hissed.

The doors opened and they sprinted up the final two flights of the service staircase to a metal door that Tom swiped open. The helicopter was already there, its rotors buffeting them with a wash of hot, dusty air. Jennifer was being loaded into the rear by two paramedics, a drip attached to her arm and an oxygen mask over her face. Ortiz was crouching on the ground, his shirt covered in her blood, his head in his hands.

‘I’m going with her,’ Tom shouted over the throb of the engines.

‘No way,’ Stokes called back. ‘You’re the only person who can ID the gunman. I need you here.’

‘I wasn’t asking for your permission.’

Keeping his head down, Tom sprinted across the pad and hauled himself in behind the stretcher, slamming the door shut after him. The pitch of the engines deepened as the pilot throttled up and with a lurch they rose into the sky.

‘How is she?’ Tom called to one of the medics as they hooked her up to a mobile ECG, her pulse registering with a green blip on the screen and a sharp tone – Beep…beep…beep. Around them power and warning lights from other machines flashed and sounded intermittently.

‘Who are you?’

‘A friend.’

‘She’s lost a lot of blood…we need to get her into theatre ASAP.’

‘Is she conscious?’

‘In and out. Try talking to her. Keep her awake.’

Tom shuffled forward until he was sitting next to Jennifer’s head. The glow of the ECG screen was staining her skin green. Her eyes flickered open and he was certain that he saw a smile of recognition tremble across her face.

‘Hold on, Jen,’ he whispered, pressing his lips to her ear. ‘We’ll be there soon.’

She nodded weakly. He brushed the hair out of her eyes, speaking almost to himself.

‘You’re going to be okay. I’ll make sure you’re okay.’

Beep…beep…beep.

He smiled at her reassuringly, glad that she couldn’t see the paramedics’ grim-faced expression as they worked on the wound, the blood still oozing from her chest. He felt her hand reach for his, press something hard and rectangular into it, her grip tightening as she pulled him closer, her mouth moving under the oxygen mask.

He bent over her, straining to hear her voice against the chop of the rotors and the rhythmic pinging of the heart monitor. He caught something, the fragment of a word, perhaps more, and then her eyes closed again and her grip loosened, allowing him to slip what she had given him into his pocket.

‘Come on, Jen,’ Tom called, shaking her arm gently at first and then with increasing urgency. ‘We’re nearly there now. You’re going to be okay. You just need to keep listening to me. Listen to my voice.’

He shook her again, more roughly this time. But there was no reaction and all he could hear was the gradual, almost imperceptible lengthening of the gaps between each tone of the ECG.

Beep…beep. Beep…beep. Beep…beep.

‘Help her,’ Tom shouted angrily to the paramedics. ‘Do something.’

They swapped a glance, one of them wiping the back of his hand across his brow, smearing blood.

‘We’ve done what we can.’

Far below, the city’s neon carpet unravelled into the distance. But from up here, Tom could see that it ended, that a black line had been drawn across the desert at the city’s limits, and that beyond that was only darkness.

He leaned forward, his lips brushing against her cheek. He knew now that it was just him and her. Him and her and the hiss of the respirator and the unfeeling pulse of the ECG’s electronic heart.

‘Stay with me,’ he whispered.

For a second he could have sworn that her breathing quickened. Then the machine gave a piercing shriek. The monitor showed a perfectly flat line.

Via Galvani, Testaccio, Rome

18th March – 3.12 p.m.

The speaker crackled into life.

‘Mitto tibi navem prora puppique carentem.’

Allegra hesitated, her mind racing. She understood the Latin, of course – I send you a ship lacking stern and bow. But what did it mean? How could a ship not have a stern and a bow? Unless…unless it was referring to something else. To the front and the back? The beginning and the end? The first and the last? Latin for ship was navem, so if it was missing its beginning and its end, its first and last letters perhaps…

‘Ave,’ she replied with a smile. Latin for hello.

‘Ave, indeed,’ the voice replied with a chuckle. ‘Although I can’t claim the credit this time. That was one of Cicero’s.’

The door buzzed open and Allegra made her way to the lift, smiling. She’d first met Aurelio Eco at La Sapienza, before heading off to Columbia for her Masters, where he’d been a visiting professor in the university’s antiquities department. Before that, he’d spent fifteen years as the Director of the Villa Giulia, Rome’s foremost Etruscan museum, during ten of which he had also headed up the Ufficio Sequestri e Scavi Clandestini, the Office of Clandestine Excavations and Seized Objects. Unfortunately for her, these posts seemed to have provided him with an inexhaustible supply of riddles, which he delighted in asking her as a condition of entry to his apartment. A latter-day Sphinx to her Odysseus.

As usual the door was open and the kettle boiling. She made herself a strong black coffee and Aurelio an Earl Grey tea with lemon, an affectation of his from a brief stint at Oxford in his twenties that he had never been able, or wanted, to shake off.

He was waiting for her in his high-backed leather chair, the split in the seat cushion covered by a red-and-white keffiyeh purchased during an exchange posting to Jordan. His dusty office was full of such mementoes – photographs of him at various digs over the decades, framed maps and faded prints, prayer beads and inlaid boxes picked up in dusty Middle-Eastern souks, fragments of inscribed Roman tablets, shards of Etruscan pottery, carved remnants of Greek statues. At times it seemed to Allegra that his entire life was held in this small room, each piece invested with a particular meaning or memory that he only had to glance at or hold to live all over again.