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 and fast. Faced with the repercussions of their public disagreement, Luther orders Ripley to investigate the murder of the internet tormentor (Jared Cass) on his own.
Meanwhile, he throws himself into a mountain of cold case files, determined to connect the past and present in order to predict the fetishist's next move. Can he win this battle of wits in time to prevent the next horror? Ripley must choose whether to turn a blind eye to Luther's unorthodox policing or go on record, while Stark's obsession with Luther deepens and DCI Gray finds that the line between right and wrong is becoming increasingly blurred.