When a well-dressed couple, claiming to be social workers, appear at Brenda Scupham’s door, saying they must take her seven-year-old daughter, Gemma, into care after allegations of abuse, Brenda is confused and intimidated enough to hand the child over. But when the couple, Mr Brown and Miss Peterson, fail to bring Gemma home, Brenda realizes she has made a terrible mistake. As the days go by, Detective Chief Inspector Banks begins to lose hope of finding Gemma alive. Then a rambler finds a body in the ruins of an old lead mine, and the two cases begin to converge in a terrifying way, leading Banks to a showdown with one of the most chillingly evil criminals he has ever come up against.