When the decomposed body of a young woman is found near railway tracks just outside Bristol one hot May morning, all indications are that she's committed suicide. That's how the police want it too; all neatly squared and tidied away.

But DI Jack Caffery is not so sure. He is on the trail of someone predatory, someone who hides in the shadows and can slip into houses unseen. And for the first time in a very long while, he feels scared.

Police Diver Flea Marley is working alongside Caffery. Having come to terms with the loss of her parents, and with the traumas of her past safely behind her, 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 for comfort - but it's so horrifying that she knows nothing will ever be the same again.

And that this time,no one - not even Caffery - can help her ...