Each file on the floor stood for an unsolved murder. He stared at one green envelope, its corner obscured by a whorl of carpet fluff. It represented a pile of about twenty boxes of files either stacked on an office floor, or bulging out of a cupboard, or locked up, gathering mould in a damp police garage in a station in the area where the murder had happened. It was the open file on a gay vet called Richard Ventnor, battered to death in his surgery twelve years ago.

It contained scene-of-crime photographs, forensic reports, bagged evidence, witness statements, transcripts – all separated into orderly bundles and secured with coloured ribbon. This was part of his current brief, to dig back into the county’s unsolved murders, liaise with the CID division where the crime had happened, looking for anything that might have changed in the intervening years that could justify reopening the case.

He knew most of each file’s contents by heart – a benefit of the memory that had propelled him through exams both at school and in the force. To him, each stack represented more than just a human life that had been taken – and a killer who was still free – it symbolized something very close to his own heart. It meant that a family had been unable to lay its past to rest because a mystery had never been solved, justice had never been done. And he knew that with some of these files being more than thirty years old, he was the last hope the victims and their relatives probably had. There was just one case where he was currently making some real progress. Tommy Lytle’s.

Tommy Lytle was Grace’s oldest cold case. At the age of eleven, twenty-seven years ago, Tommy had set out from school on a February afternoon, to walk home. He’d never been seen again. The only lead at the time had been a Morris van, seen by a witness who had had the presence of mind to write down the number. But no link between the owner, a weirdo loner with a history of sex offences on minors, had ever been established. And then, two months ago, by complete coincidence, the van had showed up on Grace’s radar when the classic car enthusiast who now owned it got stopped for drunken driving.

The advances in forensics from twenty-seven years back were beyond quantum. With modern DNA testing police forensic scientists boasted, not without substance, that if a human being had ever been in a room, no matter how long ago, that given time they could find evidence to prove it. Just one skin cell that had escaped the vacuum cleaner, or a hair, or a clothing fibre. Maybe something one hundred times smaller than a pinhead. There would be a trace.

And now they had the van.

And the original suspect was still alive.

Forensics had been through that van with microscopes, but so far, as a disappointing lab report Grace had read last night at home informed him, they had found nothing to link the van to the suspect. The forensic Scenes of Crime team had found a human hair, but the DNA was not a match.

But they would find something in that damned van, Grace was determined, if he had to pull the vehicle apart millimetre by millimetre himself with a pair of tweezers.

He took a swig from his bottle of mineral water, grimacing at the taste – or lack of taste – the sheer, faintly metallic nothingness of the stuff he was drinking in an effort to wean himself off his usual gallon of coffee a day. Then, replacing the cap, he stared at the gathering rain clouds, heavy as suet, suspended low above the grey slab of the Asda roof across the road that was most of his view, thinking about tomorrow.

It was Thursday tomorrow and he had a date – not like the last, disastrous bunny boiler of a blind date from an internet agency – but a real one with a beautiful woman. He was both looking forward to it and nervous at the same time. He was fretting about what to wear, about where to take her, whether he’d have enough to say to her.

And he was concerned about Sandy. About what she would think about him dating another woman. Absurd, he knew, to be thinking these thoughts after almost nine years, but he couldn’t help it. Just as he could not help wondering, almost every moment of his waking life, where she was, what had happened to her. Whether she was alive or dead.

Clutching the plastic Evian bottle he took another long swig, then stared over the top of the piles of out-of-control paperwork on his desk at his computer screen, then down at a stack of this morning’s papers. The headlines of the top one, the local paper the Argus, screamed out at him: Two Dead in Sussex Police Chase.

He dumped the newspapers on the floor and scanned the latest deluge of emails. He was still just getting the hang of the new Vantage software for the force’s system, which was a lot easier to use than the GreenScreen it replaced. Grace checked the incident reports log to see what had happened during the night, which normally he would have done first thing, but today he’d had to prepare for the press conference.

There was nothing out of the ordinary, just the usual detritus of a Brighton midweek night and morning. A handful of muggings, break-ins, car thefts, a hold-up at an all-night grocery store, a pub fight, a domestic, a bunch of RTAs – no fatalities – a call-out to farmland near Peacehaven to investigate a suspicious object. No major incidents, no serious crimes, nothing to grab his interest.

Good. He’d been out of the office most of the past week, apart from some hours he had had to spend in preparation and in court on the ongoing trial of a local villain, and needed a few days to catch up on his paperwork.

He synced his Blackberry with the computer and checked his diary. It was still clear. His secretary, Eleanor Hodgson – or Management Support Assistant as the political correctness Politburo now dictated she be called – had wiped all his appointments to let him concentrate on his case and the trial. But his diary would fill up soon enough, he rued.

Almost immediately there was a rap, then his door opened and Eleanor came in. Prim and nervy, fifty-something, she looked the kind of backbone-of-England woman Grace imagined one would meet at a vicar’s tea party – not that he had ever actually been to one. And after three years of working for him, Eleanor was still unfailingly polite and a tad formal, as if she was nervous of upsetting him, although he could not imagine why.

She stood holding a wodge of newspapers at arm’s length as if concerned they might pollute her. ‘Oh, Roy,’ she said. ‘I, er… these are later editions of some of the morning papers; I thought you might want to see them.’

‘Anything new?’

‘More of the same. The Guardian has a quote from Julia Drake at the Independent Police Complaints Commission.’

‘I didn’t think it would be long before they started. Self-righteous fucking cow.’

Eleanor flinched at his swear word, then smiled nervously. ‘Everyone’s being a bit harsh on you, I think.’

He glanced at his water, suddenly craving a cup of coffee. And a cigarette. And a drink. It was nearly lunchtime and he usually tried to avoid drinking until the evening, but he had a feeling he was going to break that rule today. The Independent Police Complaints Commission. Terrific. How many hours of his life was that going to consume over the coming months? He had known it was inevitable they would get involved, but having it confirmed seemed, suddenly, to make everything worse.

His phone rang. He answered it as Eleanor stood there, and heard the Chief Superintendent’s crisp Mancunian accent.

‘Well done, Roy,’ Gary Weston said, sounding even more like his superior than ever. ‘You handled yourself well.’

‘Thanks. We’ve now got the IPCC to deal with.’

‘We’ll sort them. Are you free at three?’

‘Yes.’

‘Come to my office – we’ll work on a report for them.’

Grace thanked him. The moment he hung up, the phone rang again. This time it was the Force Control Room. A civilian dispatcher called Betty Mallet, who had been there as long as he could remember, said, ‘Hello, Roy, how you doing?’