A sadistic killer. An infamous victim. A crime that gets darker and darker ...

The body of a young woman is found in a London hotel room, the victim of a suspected poisoning. Called in to investigate, DI Simon Fenchurch soon discovers the case is far more sinister than he could have imagined.

He should have recognised the woman at once - a teacher at a local school, her scandalous affair with a pupil has been splashed across the tabloids. As Fenchurch interrogates those closest to her, a web of suspicious connections begins to emerge.

Meanwhile Fenchurch's own life is still in turmoil: his family fragmented, his baby son in intensive care, and his mentor replaced by an unsympathetic new boss. The streets of London are in chaos too, with a spate of acid attacks on seemingly random victims.

Struggling to hold on to hope on both fronts, Fenchurch faces the toughest few days of his career. Can he keep his family safe and catch whoever is behind the murder before more lives are lost?