BBC One’s Rellik is a murder mystery with a difference: it tells the story backwards. Gemma Dunn finds out how leads Richard Dormer and Jodi Balfour rose to the challenge

CREATED by the writers behind cult hit The Missing, it goes without saying viewers tuning into Rellik are in for a bumpy ride. Penned and produced by Harry and Jack Williams, the BBC One crime thriller - the title of which is 'killer' spelled backwards - puts Richard Dormer in the starring role as DCI Gabriel Markham, who is propelled in an obsessive hunt for a serial killer who left a mark on him both physically and mentally.

Yet forget the well-trodden format of a cop on a wild goose chase to nab the offender - Rellik is a page-turner with an inbuilt structural conceit that turns the story on its head by starting at the end. With a prime suspect caught, the six-part series moves backwards in time through the string of gruesome murders, gradually unravelling the truth.

"Just when you think you've got a hang on it, it's like the ground comes out from under your feet and you find yourself going backwards," says Dormer, whose disfigured character is joined by DI Elaine Shepard (Jodi Balfour) in his pursuit for justice. "It's absolutely crazy. It's like a puzzle that comes together and I think some people will enjoy it more than others - those people who love thrillers, who love to pick holes."

While Dormer agrees starting at the end and finding your way back to the beginning is a "completely original way of storytelling", he is the first to declare the format comes with its own challenges.

"You're jumping backwards and forwards, but largely you have a journey," says the Game of Thrones actor, 47. "Whereas with this we were constantly going, 'Where have I been?' 'Where am I going?' and trying to remember everything that was about to happen, rather than what happened. It's so weird, it scrambled my head. It was exhausting and mentally tough to keep an eye on the ball."

"As actors, we had to play the truth of it, we had to play the reality of it, which is chronological," says Balfour, 29, who makes up a stellar cast including Rosalind Eleazar, Paterson Joseph and Paul Rhys. "I didn't think about suspense building or anything like that all that much, I tried to honour the moment. But that said, it was really fun to see some of the rewind inserts after filming them," adds The Crown star. "They're really visually evocative."

The plot's not the only ambiguous ingredient, however, as audiences will find out the complex characters have a lot to answer for too.

"With Rellik everybody is faking - there's secrets to be had with everybody," explains Balfour, whose persona embarks on a steamy affair with the protagonist. "But certainly Elaine is not a wear-everything-on-her-sleeve kind of gal. Not with anybody in her life. The thing that I really wanted to do, which I never get to do, is play someone who is quite tormented as a human being. And her whole life has been pretty dark and difficult, so that was really exciting."

"Gabriel is a pretty unpredictable, scary guy," says Dormer, of his own character's turmoil. "He's scary because of his absolute intense conviction that he will do anything and break any rule to get this guy who has done this to him." He's nothing like the officer he played in Fortitude: "He's another damaged individual, but he's totally different this guy," he compares. "The weird thing about this person, I discovered, is that I am almost playing myself but in an alter-reality which is very interesting."

Exposing himself in that way was daunting in itself, says Dormer.

"The one thing I have done with every character I have ever played is I've crawled into somebody else," explains the Northern Irish star. "I become this other thing, which is really liberating because then you have no fear of showing the ugliness or whatever because you're a different person. But if you're playing yourself, kind of yourself, it's a lot rawer. It can be very truthful and that's pretty scary, but it's all part of it."

Was he able to leave Gabriel at the door once filming wrapped?

"No, that's the problem!" Dormer relays. "You're supposed to with these kinds of parts; you've got to debrief every night but the closer the character is to you, the lines start to blur and that's harder to do because you start forgetting - 'Wait a minute, which part is not real?' You do absorb it," he continues, revealing he'd sit down to classical music with a large glass of red wine to unwind. Actually that's done something to your psyche. It's invaded some part of you and shaken things up."

South African-born Balfour, on the other hand, preferred to keep Elaine at arm's length.

"It's difficult to get into the depths of the nature of the role, but I'm such a wuss when it comes to anything remotely scary," confesses the actress. "I don't watch horror films, I barely watch thrillers and this character has been so dark and twisty that I have my real boundaries. I set boundaries for myself. The most boring and laughable of which is that I don't really work at night on the script. Obviously we work at night, but when I was prepping or if I'm ever running lines I just don't work at night, as anytime close to bed it has really been affecting my dreams and my sleep and all sorts of stuff. But no, I have a completely separate life to this character and I really work at maintaining that, because it wouldn't be a fun way to spend five and a half months."

"I think probably looking back it will have changed me" confides Dormer. "And also the responsibility of playing a lead in a big thing like this... What doesn't kill you makes you stronger!"

  • Rellik premieres on BBC One on Monday, September 11.