A building was on fire, he realized. Then, through his shock and horror, his heart sank as he realized which building. The World Trade Center.

Shit, shit, shit.

Chilled and confused like everyone else, he stood rooted to the spot, still not able to believe his eyes or comprehend what he was seeing.

The stop light turned green and, when the cars and vans and a truck started moving forward, he wondered if maybe the drivers hadn’t noticed, that perhaps they could not see up above the tops of their windscreens.

Then the plume thinned for a few moments, the smoke fanning out. Through it, standing tall and proud against the brilliant blue of the sky, was the black and white radio mast. The North Tower, he recognized, from a previous visit. He felt a flash of relief. Donald Hatcook’s office was in the South Tower. Good. OK. He would still be able to have his meeting.

He heard the wail of a siren. Then a whup-whup-whup, getting louder, deafeningly louder, echoing all around in the silence. He turned and saw a blue and white NYPD patrol car with three occupants, the guy in the back leaning forward, craning his neck upwards. It hurtled urgently past on the wrong side of the road, roof spinners showering red sparks on the doors of three yellow cabs in a row. Then, braking hard, tyres squealing, its nose dipping, it wormed its way through the intersection, between a bakery delivery truck, a halted Porsche and another yellow cab.

‘Oh, my God! Oh, Jesus! Oh, my God!’ a woman somewhere close behind him was saying. ‘Oh, my God, it hit the tower! Oh, my God!’

The siren receded into the distance, just audible above another long silence. Chambers Street had fallen quiet. It was empty, suddenly. Ronnie watched a man walk across. He was wearing a baseball cap, lightweight anorak and workman’s boots, and carrying a plastic bag which might have contained his lunch. He could hear the man’s footsteps. The man stared warily down the empty street, as if worried he might get run over by a second cop car.

But there was no second cop car. Just the silence. As if the one that had gone past was enough and could deal with the situation like it was some minor incident.

‘Did you see it?’ the woman behind him said.

Ronnie turned. ‘What happened?’

She had long brown hair and eyes that were bulging. Two bags of shopping lay on the sidewalk either side of her, cartons and tins of stuff spilled out.

Her voice was quivering. ‘A plane! Oh, Jesus, it was a fucking plane! It hit the fucking tower. I can’t believe what I saw. It was a plane. It hit the fucking tower!’

‘A plane?’

‘It hit the tower. It hit the fucking tower.’

She was obviously in shock.

There was another siren now. Different from the cop car, a deep honking sound. A fire tender.

This is great! he thought. Oh, this is just so bloody great! The morning I have my meeting with Donald, some fucking jerk crashes his plane into the fucking World Trade Center!

He looked at his watch. Shit! It was almost 8.55! He’d left the deli just after a quarter to – giving him plenty of time. Had he really stood here for ten minutes? Donald Hatcook’s snotty secretary told him he needed to be punctual, that Donald only had an hour before he needed to leave for the airport to catch a plane to somewhere – Wichita, he thought she’d said. Or maybe it was Washington. Just one hour. Just a one-hour window to pitch to him and save his business!

He heard another siren. Shit. There was going to be fucking chaos, for sure. The bloody emergency services might seal the whole area off. He had to get there before they did. Had to get to that meeting.

Have to.

There was no way he was letting some fucking jerk who crashed his plane bugger up his meeting!

Towing his bags behind him, Ronnie broke into a run.

There was an unpleasant smell in the storm drain that had not been here yesterday. A putrefying animal, probably a rodent. Roy had noticed it when he first arrived, shortly before 9 a.m., and now, an hour later, he wrinkled his nose as he re-entered the drain, holding two bulging carrier bags of hot drinks foraged from a nearby Costa by a young, eager-to-please Police Community Support Officer.

The rain drummed down relentlessly, turning the ground outside into more and more of a quagmire, but, Grace realized, there was still no rise in the water level here. He wondered how much rain that would take. From his memory of the body of a young man found in the Brighton sewer network some years ago, he knew that all the drains connected into a trunk sewer that flowed out into the sea at Portobello near Peacehaven. If this drain had flooded, then it was likely that much of the evidence, in particular the victim’s clothes, would have been washed away long back.

Ignoring a couple of sarcastic comments about his new role as tea boy, his nerves ragged from his disturbed night and troubled thoughts about the skeleton, Roy began distributing the teas and coffees to the team, as if by way of apology – or atonement – for ruining their weekend.

The storm drain was a hive of activity. Ned Morgan, the POLSA, several search-trained officers and SOCOs, all in white suits, were dispersed along the tunnel. They were searching inch by inch through the mulch for shoes, clothes, items of jewellery, any shred or scrap, however small, that might have been on the victim when she had been put down here. Leather and synthetics would have the best chance of surviving in this damp environment.

On their hands and knees in the gloomy brick drain, in the chiaroscuro of shadows and brightness thrown by the lights that had been rigged up at intervals, the team made an eerie sight.

Joan Major, the forensic archaeologist, who was also encased from head to foot in a white suit, was working in silent concentration. If this ever came to trial, she would have to present to the court an accurate 3-D model of the skeleton in situ. She had just finished darting in and out, struggling with the lack of signal for the hand-held GPS device she was using to pinpoint and log the coordinates of the remains, and was now sketching the exact position of the skeleton in relation to the drain and the silt. Every few moments the flash from a SOCO photographer’s camera strobed.

‘Thanks, Roy,’ she said almost absently, taking the large latte he handed her and setting it down on a wooden box full of her equipment that she had placed on a tripod structure to keep dry.

Grace had decided he would make do with a light team over the weekend and then gear up on Monday morning. To Glenn Branson’s immense relief, Grace had given him the weekend off. They were working in ‘slow time’; there wasn’t the urgency that would apply if the death had been more recent – days, weeks, months or even a couple of years. Monday morning would be soon enough for the first press conference.

Maybe he and Cleo could still make their dinner reservation in London tonight and salvage something of the romantic weekend he had planned if – and it was a huge if - Joan got through her mapping and recovery process and the Home Office pathologist was able to do his post-mortem quickly. Some hope, he knew, with Frazer Theobald – and actually, where the hell was he? He should have been here an hour ago.

As if on cue, clad in white like everyone else in the drain, Dr Frazer Theobald made his entrance, warily, furtively, like a mouse scenting cheese. A stocky little man just under five feet two, he sported an untidy threadbare thatch of wiry hair and a thick Adolf Hitler moustache beneath a Concorde-shaped hooter of a nose. Glenn Branson had once said that all he needed was a fat cigar to be a dead ringer for Groucho Marx.