This is a welcome return for Mo Hayder to writing about DI Jack Caffery, last seen in THE TREATMENT and is no less disturbing than her previous novels. The main difference is the setting which has moved from London to Bristol. In addition, having been separated from his damaging past by the new location he now has a new partner who has a disturbing past of her own.

Sergeant Phoebe "Flea" Marley is the police diver on the case of the dismembered hand; found in the old harbour in Bristol's city centre Flea and the other divers search for the rest of the body, but discover nothing till they find its pair under a local restaurant, and further investigation reveals that the hands' owner may still be alive. The investigation uncovers links with drug dealing and some more disturbing "trading" of gruesome artefacts including body parts.

As well as battling this mysterious case with its elements of drug abuse and possible African religious rituals, Caffery and Flea are also confronting their own ghosts. Flea is handling the death of her parents in a diving accident and their missing bodies and Jack is still struggling with the death of his brother at the hands of a paedophile many years in the past. Jack's encounters with "The Walking Man", an itinerant ex-con who killed the man who abused and murdered his own child, keeps Caffery revisiting his past and focusing on what he did not do to avenge his brother.

There is not a natural chemistry between these two partners, although they are suffering from similarly painful family histories, which means that it does not make them easily readable, certainly not the bantering relationship of the traditional detective "team" we are so familiar with. The plot has some untied ends and starts a little slowly, but then as readers we are drawn into the seamier side of Bristol: a dark underworld of child prostitution, drugs and violence. However, even as a veteran crime reader, I was surprised by the climax which is exciting and thrilling, as solutions are unravelled.

Hayder has a really graphic writing touch and her elaborate descriptions of the experiences of diving and the gruesome results of the killer's work make this unsettling reading. The personal agonies of the two main players are compelling, if obsessive, but the main draw of this novel is the imaginative and lucid writing and the way in which Hayder involves the reader in her plots and makes them work hard to connect the dots.