This film opens with mass in a Boston Catholic church, where Irish American fraternal twin brothers Connor McManus (Sean Patrick Flanery) and Murphy McManus (Norman Reedus) pray while a sermon is read, mentioning Kitty Genovese, a real-life crime victim brutally murdered while her neighbors watched without intervening. As the priest begins his homily, the brothers approach the altar and kiss the feet of a crucifix. They depart as the priest reminds the congregation that they should fear not just evil but also the 'indifference of good men'. The brothers conclude that the priest finally understands, Connor stating, 'I do believe the Monsignor's finally got the point...' and Murphy replying, 'Aye'.
Connor and Murphy work at a local meatpacking plant. While celebrating St. Patrick's Day in a neighborhood bar, three Russian 'soldiers', led by Ivan Checkov, enter and order everyone to leave, as their organization has decided to evict the pub. In the ensuing bar brawl, Connor, Murphy, and the patrons publicly humiliate the mobsters, who the next day ambush the brothers in their home. As Murphy is dragged into a nearby alley to be executed, Connor escapes to the roof and drops a toilet, along with himself, off the roof and onto the mobsters, killing them and rescuing Murphy.
The Russian mob's involvement summons FBI agent Paul Smecker (Willem Dafoe) to the murder case, and he surmises that the mobsters' death was not a professional hit but self-defense. As the police begin a manhunt for the killers, Connor and Murphy arrive at the police station to clear their names. During the initial interrogation, the brothers impress Smecker with their multilingualism (including Gaelic, Russian, French, Spanish, Italian, and German) while recalling the specifics of the barfight and subsequent self-defense the next morning. Smecker believes their story and allows them to stay overnight in a holding cell to evade the press. That