Saoirse Ronan, Sam Rockwell and David Oyelowo are to star in a new murder mystery thriller.

The trio have boarded the cast of the untitled project, which is being directed by Tom George – who has previously helmed the BBC comedy series 'This Country'.

The movie is set in 1950s London, where a desperate Hollywood film producer hopes to turn a popular West End play into a film. When members of the production are murdered, world-weary Inspector Stoppard (Rockwell) and overzealous rookie Constable Stalker (Ronan) find themselves in the midst of a puzzling whodunit within the city's glamorous Theatreland and sordid underground.

'Iron Lady' producer Damian Jones will produce for Searchlight Pictures after previously working with the studio on films such as 'Belle' and 'Absolutely Fabulous: The Movie'.

Mark Chappell has written the script for the project but a production date is yet to be announced.

Saoirse has a number of intimate moments with co-star Kate Winslet in her latest movie 'Ammonite' but revealed that she doesn't get nervous about filming sex scenes.

The 26-year-old actress said: "I've been very lucky that I've never felt overly nervous doing sex scenes.

"To me, they're so completely technical. It's not like a kissing scene, where you're actually kissing someone. It's purely technical and choreographed. I've just always sort of seen it as that, which I think is probably a good way to go about it."

Director Francis Lee allowed the two stars to choreograph the scenes themselves and Saoirse revealed that she and Kate had "fun" putting them together.

She explained: "In terms of a sex scene between two women, the two of us naturally took the lead. We know what we like, really, and we could have an open conversation about that.

"We talked through the progression from one sex scene into the next and how the characters needed to take it a step further each time.

"But definitely, being able to lead the conversation and take it in the direction we felt comfortable with was wonderful.

"And it was fun! It was really fun to go, 'Well, what about this? And what if you do that?' I think that was a new experience for both of us."