Turning her Peugeot into Castleton Road, Fry stopped at the little corner shop run by an Asian family. The young couple had always been pleasant to her, even when she hadn’t been in a mood to reciprocate. A friendly greeting could be welcome at times.

She wasn’t really hungry, but she bought enough supplies to keep body and soul together for another twenty-four hours. Cheese and toast would satisfy her. Anything else would sit uncomfortably on that tight, anxious knot in her stomach. She passed over the cakes and chocolate displays, and instead picked up a yogurt. And not just any yogurt, but an organic bio-live luscious low-fat fruit yogurt, raspberry and cranberry flavour. She felt strangely virtuous.

Groups of young men and women tottered or staggered around the pubs on the corner of Grosvenor Avenue, some of them with tinsel in their hair or reindeer antlers on their heads. It was Saturday night, of course. She’d forgotten that. At weekends, some of her fellow flat-dwellers lived dangerous and unpredictable private lives. Not her concern when she was off duty, though.

‘Just stay out of my way, or I’ll run you over,’ she muttered at a drunk who stumbled off the kerb into the path of her car. What difference would another dead body make?

But a fresh body was a different matter from aged remains. Pity Wood Farm was a classic historical case. Fry knew that most of the evidence in any historical investigation was found in the form of layers. It didn’t matter whether you were researching your family history, or hunting for a serial killer. There would be layers on top of each other – different levels of meaning and significance. Over the years, meanings distorted and accumulated irrelevant associations. An enquiry had to dig down to the lowest level to find the one that was most accurate, the most free of irrelevant material. A good bit of digging, that was what she needed. But psychological digging, not the knee-deep-in-mud type.

She was aware that the lorry driver, Jack Elder, might turn out to be a complete red herring. But it was comforting to have someone in custody. Anyone. At least there would be charges at some point.

But somewhere, waiting to be dug up, were the identities of the two victims at Pity Wood Farm. They couldn’t remain Victim A and Victim B, a couple of reference numbers in the anthropologist’s report, and a Forensic Science Service casework enquiries code. They had been human beings once, and they were owed a proper identity.

The body that Jamie Ward discovered had made the message clear. Fry wouldn’t forget that grey hand, bent in a pathetic summons, coaxing her towards the grave, and ensuring that she could never turn her back on it.