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.

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.

Jack and Charlie are called out in the early hours after a 13-year-old girl is stabbed. The hospital reports back that she was eight weeks pregnant, shows signs of possible self-harming and had been previously sexually assaulted, while a number on her mobile phone belongs to the cab driver who drove her to hospital and claimed he did not know her.