Four-year-old Ellen is snatched by a stranger in the dead of night. Her devastated mother, Nicole, receives four identical phials and a threatening note in a familiar scrawl that chills her to the bone. But she always knew this would happen. She's been expecting it for years... According to the note, one of the phials is poisoned. Nicole is given a deadly challenge : if she drinks one, the sadistic kidnapper will notify the police of Ellen's location. The sender claims to be Luka Volkov but Luka is supposed to be dead, killed long ago in a fire that haunts all those involved. DI Amy Winter is still reeling from the discovery that she is the daughter of a serial killer, and her childhood trauma only makes her more determinated to bring Ellen home. When another child is taken, Amy finds herself in a race against time. To rescue the children, must she seek help from the one person she wants to forget?