Keira Knightley has joined the cast of Morten Tyldum's indie drama The Imitation Game.

Based on a biography by Andrew Hodges titled Alan Turing: The Enigma, the film tells the true story of U.K. mathematician and cryptographer Alan Turing (Benedict Cumberbatch). The math genius played a key role in cracking the German's enigma code machine, giving the allies an advantage during the tail end of the the second World War. He was later prosecuted for being a homosexual and ended up killing himself.

Keira Knightley will be portraying a friend of the mathematician, who helps him until his untimely demise. Morten Tyldum is directing from a script penned by Graham Moore. Teddy Schwarzman, Nora Grossman and Ido Ostrowsky are producing.

No production schedule has been released.