During a hypnotherapy session with new client, Jon, Susannah learns he kills girls and is planning to kill tonight. Jon escapes but Susannah is determined to stop him at all costs.
Susannah is thrown when her ex-lover and DSI, Richard and his wife, Natasha, don't take her concerns about Jon seriously and realises they're hiding something.
At a Police Firing Range, Susannah finds ex-client Louisa, who's cold at first but finally admits she was forced to drop a murder case and sends Susannah a photo of the witness.
Susannah reels to learn her ex-husband, Danny, has fallen from the roof of his psyche unit. But she soon realises he was pushed and 'kindly' Dr Underwood is trying to cover it up.
Susannah tracks down the witness, an escort called Sapphire. But Susannah reels when she learns the girl Jon killed was Christina, her daughter, and Sapphire is Jon's next target.
Susannah seeks out ex-client and Royal Marine, Joseph. She and Joseph head down the Thames, looking for Sapphire, but the gunmen catch up with them and Joseph is shot.
Susannah tracks Sapphire's Earbuds to her ex-colleague, Kate. Susannah soon realises Kate is involved in the conspiracy and knows where Jon has taken Sapphire.
Susannah tracks down Sapphire and Jon. In a gripping showdown, Susannah faces her daughter's killer, determined to stop him whatever the cost and save herself and Sapphire's lives.
