In the pitch dark, nine feet under water, police diver Flea Marley closes her gloved fingers around a human hand. The fact that there's no body attached is disturbing enough. Yet more disturbing is the discovery, a day later, of the matching hand – indications suggest that the victim was still alive when they were removed. Flea and DI Jack Caffery soon establish that the hands belong to a boy who has recently disappeared. Their search for him - and for his abductor - lead them into the darkest recesses of Bristol's underworld, where drug addiction is rife, where street-kids sell themselves for a hit, and where an ancient evil lurks.