The Departed is set in South Boston, where the state police force is waging war on organized crime. Young undercover cop Billy Costigan (Leonardo DiCaprio) is assigned to infiltrate the mob syndicate run by gangland chief Costello (Jack Nicholson). While Billy is quickly gaining Costello's confidence, Colin Sullivan (Matt Damon), a hardened young criminal who has infiltrated the police department as an informer for the syndicate, is rising to a position of power in the Special Investigation Unit. Each man becomes deeply consumed by his double life, gathering information about the plans and counter-plans of the operations he has penetrated. But when it becomes clear to both the gangsters and the police that there's a mole in their midst, Billy and Colin are suddenly in danger of being caught and exposed to the enemy – and each must race to uncover the identity of the other man in time to save himself.
This was without a shadow of a doubt the best movie to come out in 2006. I absolutely loved this movie. It was one of those crime/cop thrillers that keeps you sitting on the edge of your seat because the back and forth tension was so well directed. This is probably one of Martin Scorcese's best movies. The cast was phenomenal, especially Jack Nicholson, Matt Damon and Leonardo DiCaprio. Hell - even Alec Baldwin and Mark Wahlberg who I think are horrible actors were great in this one. This movie is right up there with Heat in my book at crime thrillers that I could see myself watching over and over again.
I very strongly recommend this movie for rental. It's also think it's totally worth the purchase out right if you so desire.