John River is a respected police officer haunted by the murder victims whose secrets he must uncover. Struggling to come to terms with the recent loss of a close colleague, River chases a potential suspect across London, with tragic consequences. In his fragile mental state, he comes under increasing pressure both from the press and within the police force as calls for his dismissal grow. Meanwhile, the mother of a murdered teenager is growing increasingly desperate - the boyfriend has confessed but no body has been found, and she blames River for failing to make good on his promise to find her daughter.

With his career and access to the Stevie case resting on the outcome of his psychiatric report, River must keep his unofficial investigations into Stevie's death to himself. This sends tensions high with his new partner Ira, who fears being dragged down by River's instability, and Chrissie, who needs River working on his own caseload, most pressingly investigating a suspicious workplace accident that has left a foreman fighting for his life.

But River's mind is elsewhere as the discovery that Stevie has been keeping secrets forces him to reassess how well he knew his best friend and colleague. Unearthing new information about who Stevie spoke with in the lead-up to her murder throws suspicion on somebody close to her - somebody with real motive.