New York, 1863, Lower Manhattan is a place of lawlessness, rampant political corruption and great unrest. With the Civil War underway, the country is torn apart and on the brink of chaos. For the inhabitants of Manhattan's notorious Five Points, a war is also raging closer to home.

Amsterdam Vallon (LEONARDO DICAPRIO), a young Irish-American immigrant, returns to the Five Points after fifteen years. There he seeks revenge against Willilam Cutting, a.k.aa. Bill the Butcher (DANIEL DAY-LEWIS), the powerful anti-immigrant gang leader who killed Amsterdam's father. Amsterdam knows the first step toward accomplishing his mission is to infiltrate Bill's inner circle. But he is also drawn to Jenny Everdeane (CAMERON DIAZ), an enigmatic pickpocket whose fierce independence and undeniable beauty fascinate him. Yet Jenny's hidden past unexpectedly complicates his plan.

Amsterdam's journey becomes fight for both personal survival and a place for his people. His struggle reaches a fevered crescendo during the 1863 Civil War Draft Riiots - the most explosive episode of urban unrest the American nation had yet seen.