Graham King is producing under his GK Films banner with Monahan and Quentin Curtis. The film will shoot this summer in and around London.
Farrell will play a South London criminal who, after release from prison, tries to give up the gangster life by becoming a handyman for a reclusive young actress.
Farrell, who just won a Golden Globe for “In Bruges,” next appears in the ensemble of the Spitfire Pictures-financed drama “The Way Back,” which Peter Weir directs in March.
Knightley next stars in “Last Night” for Miramax and is attached to play Zelda Fitzgerald in the John Curran-directed “The Beautiful and the Damned” for the Film Department.