The Departed

About the film

Contains story spoilers.

The story begins in Boston, where crime boss Frank Costello takes an interest in young Colin Sullivan and slowly steers him toward a career inside the Massachusetts State Police. Years later, Sullivan joins the Special Investigation Unit and provides Costello with information from within the department. At the same time, Billy Costigan is selected by Captain Queenan and Sergeant Dignam to infiltrate Costello’s organization. The two men move in opposite directions through the same city: Colin wears the authority of a police officer while serving the gang, and Billy earns the gang’s trust while trying to remain an officer underneath his cover.

Billy's assignment requires him to commit crimes convincingly enough for Costello to accept him. The work strains him, and Queenan and Dignam have to persuade him to stay in place when he fears he is losing control of the situation. Colin is more comfortable inside the department, where he gains influence and begins a relationship with police psychiatrist Madolyn Madden. Madolyn also becomes Billy's court-ordered therapist, so the two moles' private lives intersect through her without her knowing the full truth. The film builds tension not only around who will be identified first, but around how secrecy has shaped each man's sense of self.

The police plan a sting around Costello's sale of stolen microprocessors, but Colin helps the gang avoid it. Both the police and Costello recognize that someone is leaking information, and each side assigns its mole to find the opposing one. Billy learns that Costello is an FBI informant and tells Queenan. Colin discovers that Queenan is meeting with his undercover officer and alerts Costello's men. When Billy asks to end the operation, Queenan helps him escape but is thrown from a building to his death. During the ensuing police action, Costello's wounded associate Delahunt tells Billy that he knows he is the mole before dying himself.

After Queenan's death, the calls on Queenan's phone and Billy's information lead Colin to understand that Costello has been cooperating with the FBI. He directs the police to tail Costello, which leads to a gunfight that kills much of the crew. Costello admits he is an informant, and Colin kills him. Billy then reports to Colin and sees an envelope of information on his desk that connects Colin to Costello. He understands that the police have their own mole and escapes. Billy leaves a sealed packet of evidence with Madolyn; separately, she finds a recording he had mailed to Colin containing incriminating conversations. The revelations reach her through two distinct routes, neither of which can undo Queenan's death or stop the trap closing around Billy.

Billy meets Colin on the rooftop where Queenan died and arrests him. Brown appears at the scene, but another Costello spy, Trooper Barrigan, intervenes and kills Billy. Barrigan also shoots Brown, and Colin kills Barrigan, leaving him to be treated as Costello's only mole. Colin recommends that Billy receive a posthumous commendation, but Madolyn leaves Colin after Billy's funeral. Colin returns home to find Dignam waiting; Dignam shoots him and walks out. The film follows these consequences through a commendation, a departure, and an act of vengeance rather than a courtroom resolution.

A telling contrast appears in how both men use professional language to cover private fear. Colin can discuss procedure and surveillance in the same rooms where he protects Costello, while Billy must perform criminal confidence even when Queenan is his only reliable link back to the police. Their meetings with Madolyn create a brief space where each can speak as a person, but neither can give her a truthful account of his life. Queenan's quiet efforts to keep Billy undercover and Dignam's abrasive insistence that he stay alive represent competing ways of protecting an officer. By the time Billy identifies Colin, the department's channels for helping him have already been compromised.

The film threads its suspense through repeated handoffs of information: the microprocessor sting, phone calls, surveillance, Queenan's meeting with Billy, deleted police records, and the envelope on Colin's desk. Each clue changes meaning depending on who holds it. The police operation and Costello's crew mirror one another because both depend on watching and reporting, while the two central moles know only part of the danger closing around them. Madolyn's position sharpens that pattern: she hears Billy's fear and Colin's confidence in separate settings, yet lacks the facts to connect them before their lives collide.

Martin Scorsese and screenwriter William Monahan keep the plot moving through overlaps in surveillance, reporting, and mistaken assumptions. Costello’s crew and the police are not cleanly divided moral worlds; both use information as leverage, and both make decisions that put their people at risk. The film’s crowded ensemble helps make the institutional leak feel like a system rather than a single clever trick. By the end, one mole has been publicly exposed and another has been dealt with privately, but justice is incomplete: Billy dies before he can expose Colin publicly, and Dignam’s vengeance leaves no courtroom accounting for Colin’s crimes.