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.

The man behind the bloodshed pits both factions against one another and the team are in a race against time.

Harry and Nikki's friendship is rocked by the discovery of the body of Harry's ex-lover.

Memories of his own daughter's death are stirred up when Leo is called in to investigate the suicide of a 14-year-old girl.