Pitted against his most chilling adversary yet, Luther is haunted by past ghosts and hellbent on revenge as the Serious Crime Unit faces its most challenging psychological duel to date. There is no question he will come close to the edge, but will he finally go over?

A self-destructive near-genius, Luther might just be as dangerous as the depraved criminals he hunts. Luther follows his own moral code as much as the rules of criminal law. But he quickly becomes locked in a lethal battle of wits with Alicea, a beautiful, highly intelligent mass murderer, and his decision-making process becomes increasingly murky. Luther's lonely path pulls him towards the very edge of temptation.

In this new mini-series, a twisted fetishist is targeting young women in London. As Luther is called to another case, will the killer escape his grips? Luther faces an even bigger threat as members of his own team will stop at nothing to bring him down. And as a vigilante killer takes justice into his own hands, Luther questions his own sense of morality. Can he continue to walk the thin line between right and wrong, or has he finally met his match?...