Ireland, 1920. Damien O'Donovan is leaving for London for an internship, until the dreaded Black and Tans attack his hurling mates, killing one for not speaking English. Thus sidetracked by the Irish War for Independence, Damien is convinced by his brother Teddy to throw his lot in with the IRA. Damien is a purist, an idealist, and therefore marked for a tragic destiny, while Teddy is a fatefully pragmatic politician. These differences between the brothers propel the film through its terrible final act, as the signing of Anglo-Irish Treaty establishes the Irish Free State, splits the Republican movement, and unleashes the Irish Civil War.