The fascinatingly complex story of how Pádraig Ó Dónaill/Patrick O’Donnell, a man from the Donegal Gaeltacht with no overt political affiliations, came to shoot and kill one of the leading figures of the assassination squad The Invincibles, and Ireland’s most notorious informer James Carey, on a ship off the coast of South Africa in 1883. Piecing together details of this Irish-speaking Donegal native, alongside the compelling story of how James Carey came to betray his Invincible comrades following their murder of high-ranking state officials in Dublin’s Phoenix Park, the film constructs a dramatic canvas upon which a most unlikely character becomes a nation’s avenging angel.