Series Three: Episode 3 is the third episode of Luther, Series Three. This is the thirteenth episode of the Luther series.
Luther must confront his demons when a vigilante killer embarks on a crusade.
Luther investigates the deaths of two muggers who were killed by a vigilante while the muggers were in the process of attacking a young couple who were sitting in their car. The killer taped a messages to the mouths of the muggers. The victims have little interest in helping the police arrest the man who saved them and they soon have another dead body – also with a message taped to his mouth – hanging in Hampton Woods. The vigilante - who is soon identified as Tom Marwood – broadcasts a message over the Internet demanding justice for his wife who was raped and murdered 4 years ago. Luther knows they have little time to stop him. Marwood's next 'execution' will be very public. Meanwhile, Gray and Stark visit Luther's new girlfriend Mary. They seem intent on destroying his reputation… Gray is beginning to doubt Stark's methods.
- Idris Elba as DCI John Luther
- Warren Brown as DC Justin Ripley
- Dermot Crowley as DSU Martin Schenk
- Nikki Amuka-Bird as DS Erin Gray
- Sienna Guillory as Mary Day
- David O'Hara as DSU George Stark
- Michael Smiley as Benny Silver
- Mark Rowley as Callum
- Gemma Lawrence as Maxine
- Oliver Stark as Shaun Butler
- Ryan Calais Cameron as Steve Meredith
- Elliot Cowan as Tom Marwood
- Rupert Procter as Dennis Cochrane
- Micheal Shaeffer as Gordon Murray
- Jason Riddington as Alan Ramsey
- Michelle Duncan as Kiera Mills