Based on a true story, FBI agent Joseph Pistone (Johnny Depp) goes undercover as Donnie Brasco to infiltrate the Bonanno crime family in New York in the 1970s. Lefty Ruggiero (Al Pacino) takes Brasco under his wing and introduces him to the rest of the gang, led by Sonny Black (Michael Madsen), as Pistone begins to collect evidence on the mob. Agent Pistone finds himself spending more and more time with the mob and less time with his family, in the end needing to make the hard choice between turning in his friends (potentially resulting in their imprisonment/death) or protecting his friends and losing his family.