where does billy costigan live in the film the depart what is the city
The film takes place in Boston. Irish Mob boss Francis "Frank" Costello (Jack Nicholson) plants Colin Sullivan (Matt Damon) as a mole within the Massachusetts State Police; the two characters are loosely based on famous gangster Whitey Bulger and corrupt FBI agent John Connolly, who grew up with Bulger. Simultaneously, the police assign undercover state trooper William "Billy" Costigan (Leonardo DiCaprio) to infiltrate Costello's crew. When both sides realize the situation, Sullivan and Costigan both attempt to discover the other's identity before their covers are blown.