Luther returns to work after a traumatic arrest to investigate the murder of a former child genius's parents, and quickly deduces that their daughter is responsible. However, unable to find evidence to convict, he becomes embroiled in a battle of wits with the suspect - who has set her sights on him and his estranged wife.

Luther, suspected of murder, goes on the run to try and prove his innocence. With Alice's assistance, they set out together to exact revenge on the real killer.