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 story of the working and personal relationship between the comedians Peter Cook and Dudley Moore, a hugely popular duo in the UK during the 1960s and 1970s. Focusing primarily on Cook, the film traces the pair from their first meeting through their career as part of the Beyond the Fringe review, their television series Not Only... But Also and various other projects before their later estrangement as Moore became a successful Hollywood film star and Cook remained in the UK.