Is it good to be back, even without Ripley (Warren Brown) who was killed off in the last series?
"It was strange without him, but, without spoiling it, his presence is there. I love the show and we wanted to do something special this time. It’s different from previous ones, we’ve raised the stakes and everything is heightened because it is only two parts, which makes it more exciting and a challenge. At the end of the last one, there were unanswered questions and perhaps we answer them..."
So what state do we find Luther in?
"He’s never going to be happy, that would be a different show! He has such bad luck, so many people die around him, so we see how that has affected him. Also, London is always the backdrop, but we wanted to see what he’d feel like outside of those mean streets, so he’s on a leave of absence at a seaside cottage. It’s a breath of fresh air, but then of course the phone rings, and it is downhill from there…"
Luther ends up hunting for a cannibal killer, why is he so keen to get him?
"As long as there’s someone out there trying to get away with murder he’ll chase them, he’s like a cat with a laser pen, he just can’t stop wanting to right wrongs. This killer is also particularly disgusting, gruesome, smart and unexpected, he really increases the fear you always get in Luther."
Will we see serial killer Alice Morgan (Ruth Wilson) again (Luther reunited with her at the end of the last run)?
"Well, her presence is felt too. Something about her draws him back. The audience loves that character and I fought to keep her a part of it in some way. But we also have a new character Megan [Laura Haddock] and she really cuts an edge in the show."
And will Luther get some new clothes as he was last seen chucking his trademark overcoat into the Thames?!
"When we first see John there is no coat, but he has to put those clothes back on. It’s like the Batman outfit for me. It’s the one project where, when I show up on set, all I really need to do is put on my costume."
You recently DJ’ed for Madonna at a concert in Berlin, what was that like?
"I had a great time, she is a legend and she did an incredible show. I was standing by the curtain before I went on and I made the mistake of peeking out and there were 17,000 people looking back at me. It was such a buzz to do it."