‘Good. Alison will be pleased. I’ll let her know.’

‘Actually, I’ll let her know,’ Grace said. ‘If I need your help I will ask her, but at the moment we are all managing very well. And – I thought you weren’t actually starting until Monday.’

‘Oh, absolutely, Roy, that’s correct. Alison just felt that helping you out over the weekend might be a good way to get my eye in.’

‘I appreciate her concern,’ Grace managed to say before he hung up, boiling with rage.

‘Detective Superintendent Pewe?’ Potting asked him, with raised eyebrows.

‘You’ve met him?’

‘Aye, met him. Know his type. Give a pompous ass like him enough rope and he’ll hang himself. Never fails.’

‘Got any rope on you?’ Grace asked.

Ronnie Wilson had lost all track of time. He just stood still, transfixed, holding the handle of his bag as if it was his crutch, watching something he could not comprehend unfolding before his eyes.

Stuff was tumbling out of the sky on to the plaza and the surrounding streets. Raining from the sky. A never-ending downpour of masonry, office partitions, desks, chairs, glass, pictures, framed photographs, sofas, computer screens, keyboards, filing cabinets, waste bins, lavatory seats, washbasins, paper like letter-sized white confetti. And bodies. Bodies falling. Men and women who were alive in the air one moment, exploding and disintegrating as they landed. He wanted to turn away, to scream, to run, but it was as if a massive leaden finger was pressing down on his head, forcing him to stand still, to observe in numb silence.

He felt that he was watching the end of the world.

It seemed that every fireman and every police officer in New York was running into the Twin Towers. An endless stream entering, barging past the endless stream of bewildered men and women leaving at half-speed, staggering out as if from some other world, covered in dust, dishevelled, some with their arms or faces tracked with blood, contorted by shock. Many of them had mobiles pressed to their ears.

Then came the earthquake. Just a gentle vibration beneath his feet to start with, then more vigorous, so that he really had to grip the handle of his bag hard for support. And suddenly the zombies emerging from the South Tower seemed to wake up and quicken their pace.

They started running.

Ronnie looked up and saw the reason why. But for a moment he thought it must be a mistake. This was not possible! It was an optical illusion. It had to be.

The entire building was collapsing in on itself, like a house of cards, except-

A police car a short distance in front of him was suddenly flattened.

Then a fire engine was flattened too.

A cloud of dust like a desert sandstorm rolled towards him. He heard thunder. Rolling, rumbling, surround-sound thunder.

A whole stream of people disappeared under masonry.

The dark grey cloud was rising in the air like a storm of furious insects.

The thunder was numbing his ears.

This was not possible.

The fucking tower was coming down.

People sprinting for their lives. A woman lost a shoe, continued limping along on one foot, then shed the other shoe. A terrible tearing sound in the air, drowning out the sirens, as if some giant monster was ripping the world in half with its claws.

They were running past him. One person, then another, and another, their faces etched into masks of panic. Some were sheet-white masks, some were dripping water from sprinkler systems, some dripping blood or showering slivers of glass. Bit-part players in a weird early-morning carnival.

A BMW suddenly jumped in the air, yards from where he stood, and came down on its roof minus its front end. Then he saw the black cloud rising, tumbling straight towards him like a tidal wave.

Gripping the handle of his bag, he turned and followed them. Not knowing where he was going, he just ran, putting one foot in front of the other, towing his bag, not sure, not even caring, whether his briefcase was still on top. Running to keep ahead of the black cloud, of the falling tower that he could hear, thundering, rumbling in his ears, in his heart, in his soul.

Running for his life.

By now the lift seemed alive, like some preternatural creature. When Abby breathed, it sighed, creaked, moaned. When she moved, it swayed, twisted, rocked. Her mouth and throat were parched; her tongue and the inside of her mouth felt like blotting paper, instantly absorbing any tiny drop of saliva she produced.

A cold, persistent draught was blowing on her face. She fumbled in the darkness for the cursor button on her phone, then pressed it to activate the light on the display. She did this every few minutes, to check whether there was any signal and to bring a small but desperately welcome ray of light into her unstable, swaying prison cell.

No signal.

The time on the display read 1.32 p.m.

She tried dialling 999 yet again. But the feeble signal had gone.

With a shiver, she again read the text that had come through:

I know where you are.

Despite not recognizing the number, she knew who it was; there was only one person who could have sent it. But how did he have her number? That was what really worried her at this moment. How the hell do you know my number?

It was a pay-as-you-go phone, which she had bought for cash. She’d seen enough cop shows on television to know that was what crooks did so their calls could not be traced. These were the phones drug dealers used. She had bought it to keep in touch with her mother, who now lived in nearby Eastbourne, to see if she was OK, while pretending to her that she was still abroad and was well. Almost as importantly, the phone was so she could keep in touch with Dave – and occasionally send pictures. It was hard being apart for this long from someone you loved.

The thought suddenly occurred to her: had the sender gone to her mother? But even if he had, he wouldn’t have got her number. She was always careful to withhold it. Besides, when she had called yesterday, her mum had said nothing and sounded fine.

Could he have been following her, seen where she bought the phone and got the number that way? No. No chance. She had bought it from a small mobile phone shop in a side street off Preston Circus, where she had been able to make doubly sure no one was observing her. At least, as best she could.

Was he here in the building now? What if he was responsible for trapping her like this? And was using the time to break into her flat…? What if he was in the flat now, searching?

What if he found-

Unlikely.

She looked at the display again.

The words scared her more and more. Coils of fear spiralled inside her. She stood up in panic, pressing the cursor again as the light went off, pushing her fingers in the crack between the doors for the hundredth time, trying to force them apart, weeping in frustration.

They wouldn’t move.

Please, please open. Oh, God, please open.

The lift swayed wildly again. An image flashed in her mind of divers in a shark cage, with a Great White nosing against the bars. That’s what he was like. A Great White. A numb, unfeeling predator. She must have been mad, she decided, to have agreed to this.

If ever there had been a moment in her life when her resolve to succeed faltered, and she would willingly have traded all she had just to turn the clock back, it was now.