When the body of a young woman is found near railway tracks just outside Bristol, the police are satisfied that she's committed suicide. Although DI Jack Caffery isn't so sure. He believes he's on the trail of someone predatory who hides in the shadows, then slips into houses unseen. And for the first time in a long while, he's scared. Police diver Flea Marley is working alongside Caffery. Having come to terms with the loss of her parents, she wonders whether their relationship could progress beyond the professional. But then she discovers something that changes everything. Too close to home for comfort - it's so horrifying that nothing will ever be the same again. And this time, no one - not even Caffery - can help her.