In early 1860s New York, Irish immigrant Amsterdam Vallon is released from prison and returns to the Five Points, seeking revenge against his father's killer, William Cutting, a powerful anti-immigrant gang leader. He knows that revenge can only be attained by infiltrating Cutting's inner circle. Vallon's journey becomes a fight for personal survival and to find a place for the Irish people.

Prominent gang leader Cyrus calls a meeting of New York's gangs to set aside their turf wars and take over the city. At the meeting, a rival leader kills Cyrus, but a Coney Island gang called the Warriors is wrongly blamed for Cyrus' death. Before you know it, the cops and every gangbanger in town is hot on the Warriors' trail.