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.

Still wracked with grief at the death of his colleague, River's mental fragility is further strained as he begins to suspect that the man he chased to his death was innocent.

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, creating tension with his new partner Ira.

The investigation into Stevie's murder changes direction when CCTV footage shows her to be closely involved with an illegal immigrant who owned the car that was used in her murder; the police launch a manhunt to track him down.

Following the murder in the public library, River and Ira must track down the killer. Their journey takes them deep into the world of the undocumented migrant community in London, a world of international hostels and immigration lawyers.

As the fractured events of Stevie's murder start to swim into focus for River, the awful truth places more pressure than ever on his worsening state of mind.