William Monahan's directorial debut has just found its top cop. According to The Hollywood Reporter, Stephen Graham has signed on for London Boulevard.

Graham, who can be seen in theaters now as the gangster Baby Face Nelson in Public Enemies, will head to the other side of the law, playing the lead detective. The film centers on the relationship that forms between an ex-con (Colin Farrell) and an actress (Keira Knightley).

Oscar-winning screenwriter William Monahan (The Departed) is making his directorial debut on the film. No production schedule has been announced.