In 1920s Ireland young doctor Damien O'Donovan prepares to depart for a new job in a London hospital. As he says his goodbyes at a friend's farm, British Black and Tans arrive, and a young man is killed. Damien joins his brother Teddy in the Irish Republican Army, but political events are soon set in motion that tear the brothers apart.

The real-life story of Dublin folk hero and criminal Martin Cahill, who pulled off two daring robberies in Ireland with his team, but attracted unwanted attention from the police, the I.R.A., the U.V.F., and members of his own team.

War between two Irish youth gangs consists of removing and retrieving buttons from each other's clothing.