Colin Farrell is totally credible as a tough guy but the movie features other stunning performances like Keira Knightley and Ray Winstone, who make the film pleasant and interesting. Monahan borrows something from other famous flicks such as Martin Scorsese's The Departed and Carlito's way. The story plays out perfectly and the pleasures are many, including Farrell's reflective smiles when things go wrong and Knightley's depiction of a beautiful woman (with fame and money but always needy and selfish). Not to mention the London perfect locations and the believable depiction of the mob's underworld. The finale leaves a bit a bad taste but the story is wonderful on the whole