The team is called to a drive-by shooting outside a London nightclub. They arrive to a scene of carnage with several people dead, or dying.

With the murder of the club manager, the pathologists also determine that the club owner shot his own girlfriend, likely by accident. They also identify an unlikely suspect in the shooting of the club manager. Harry and Nikki confront Leo over his abusive and unprofessional behavior.

Harry is shocked when his former university girlfriend, Penny Harris, is brought in dead. She drove her car into a tree and the police initially suspect suicide but the autopsy reveals that the medication in her system was ground rather than in pill form, so they conclude she was likely murdered. Her husband tells the police that he thought his wife was having an affair and her parents react strangely to the news. Leo assists the police in the death of Jimmy Triangle, a conceptual artist whose latest work dealt with the death of conceptual art - and includes his own body, as he is shot through the head. The question is whether the shot was self-inflicted or not.