A two-year-old girl is abducted from her home and her dysfunctional family comes under immediate suspicion, but then a convicted child killer is also connected to the case.

Jack and Charlie investigate an assault on the owner of the Green Pit nightclub in east London and discover the victim's sister unconscious in the cellar, with blood pouring from a head wound. The detectives' efforts to piece together what happened are hampered by the lack of CCTV footage, and the case takes a confusing turn when a 19-year-old student is found dead with a flyer for the club in his pocket.

Jack and Charlie's hunt for a serial rapist becomes complicated when the latest woman to be attacked turns out to be Diane Ackerman - the wife of the station's chief superintendent Howard. A routine background check reveals that the police had recently been called to their address and Diane has a bruise on her throat that predates the rape.

Euthanasia campaigner Terence Holland is found unconscious in his penthouse flat by his doctor after an apparent drugs overdose, leading to the assumption that the terminally ill man had found someone to help him die. However, evidence at the scene prompts Martha to speculate that this could be a case of attempted murder.