Two young hoodies are shot at close range in what looks like a gangland crime. But when another man dies shortly after, Luther realises that what the three dead men have in common is a criminal record. It looks like a new killer is on the loose - a vigilante with a personal vendetta against all past offenders.
When the killer posts a video of himself online, calling for changes to the public justice system, Luther struggles to control the increased public attention. The killer is clearly on a mission and it is only a matter of time before he strikes again. The team struggle to predict who his next target might be with so many potential victims.
Luther's investigation is interrupted by a distraught Mary. She has had a visit from Stark and Gray, whose dirty tricks seem to know no bounds. Mary doesn't know what to think or where to turn, but Luther can see that there's now fear in her eyes where there had been love. Can he convince Mary to trust him again before he is called to another crime scene?
When the killer abducts a known paedophile, he invites the public to decide his victim's fate. Luther counter attacks with a similar publicity stunt, but when it doesn't go as planned Ripley and Luther find themselves thrown into the middle of an angry mob, baying for a public execution.
|DCI John Luther||Idris Elba|
|DS Justin Ripley||Warren Brown|
|Mary Day||Sienna Guillory|
|DSU George Stark||David O'Hara|
|DCI Erin Gray||Nikki Amuka-Bird|
|DSU Martin Schenk||Dermot Crowley|
|Benny Deadhead||Michael Smiley|
|Shaun Butler||Oliver Stark|
|Steve Meredith||Ryan Calais Cameron|
|Tom Marwood||Elliot Cowan|
|Dennis Cochran||Rupert Procter|
|Gordon Murray||Michael Shaeffer|
|Ian Ramsey||Jason Riddington|
|Kiera Mills||Michelle Duncan|
|Executive Producer||Phillippa Giles|