In 1846, waves of Irish immigrants poured into the New York neighborhood of Five Points. "Billy the Butcher" bands his fellow "Native Americans" into a gang to take on the Irish gang "The Dead Rabbits," organized by Priest Vallon. After a bloody clash Vallon is dead and his son ends up in a brutal reform school. In 1862, that boy returns to seek vengeance against the man that killed his father.