The film centers around Danny Quinn, a former "street kid" from South Boston, returning home to find his family deeper into organized crime than when he left, and his struggles not to fall back into his previous life.

Danny Quinn (Donnie Wahlberg) is a former "street kid" from South Boston, colloquially known as "Southie," who returns home from New York City after three years away.

He finds his mother (Anne Meara) overwhelmed with worry as her other three kids are caught up in the madness of the hardscrabble neighborhood in which drinking, sex, and fighting is the way of life.

Danny tracks down his brothers only to find out they are deeply embedded in the Irish mob in Boston and in debt to local mobster Colie Powers (Lawrence Tierney).

In his pursuit to help his ailing mother and right his family's name on the streets of Southie, Danny tracks down his old girlfriend from the neighborhood, Marianne (Amanda Peet), finding that the love he left behind still remains.

After almost a year of post-production editing and scoring by composer Wayne Sharp, the filmmakers changed the film's name to Southie at the suggestion of Donnie Wahlberg.