When the decomposed body of a woman is found by railway tracks outside Bristol, all indications are that she's committed suicide. But DI Jack Caffery is not so sure. He is on the trail of someone predatory, someone who hides in the shadows. And for the first time in a very long time, he feels scared. Police Diver Flea Marley is working alongside Caffery. Having come to terms with the loss of her parents, she's beginning to wonder whether their relationship could go beyond the professional. And then she finds something that changes everything. Not only is it far too close to home - but it's so horrifying that she knows that nothing will ever be the same again...