John Luther must catch a Satanic occult killer accused of kidnap and murder. However, with a young mother's life at stake, Luther must use all his skills to build an airtight case.

When a serial killer goes on the rampage, Luther must put his personal life aside and delve inside the murderer's mind to discover what is driving him to kill so many girls, and why.

As Luther's affection for Jenny grows, so does his determination to protect her and help her back on her feet. Baba, however, is determined to keep Luther on a tight leash. To add to Luther's difficulties, he is called in to investigate a man whose brutal and escalating murders seem to have no motive, leaving Jenny alone and vulnerable.

Luther's personal and professional life spirals out of control as he tries to cover up Toby's death and appease a suspicious Baba. He must also protect Jenny from any further harm. At work there's also a killer at large whose actions are ruled by his dice. How do you stop a man who sees life and death as a game and whose actions can't be predicted?

Luther investigates a the case of a fetishist who is murdering women which is similar to an unsolved case from the 1980s. The team attempt to catch the copycat killer, whose murderous spree has only just started.

Luther's date with Mary, and the promise of romance, is interrupted by the news of another murder. The killer has struck again - the number of victims is escalating fast.