Beginning with the very first film footage shot in Ireland, this two-part (1916-1969 and 1969-1995) documentary tells the history of Ireland - using only original archival materials. The history of the island, the struggle for Independence, the Civil War, partition, and 25 years of conflict in the North since 1969 are recounted.

The film relies upon original, contemporaneous and often previously unseen newsreel and documentary materials. Including footage from the Easter Uprising and its aftermath, of the newly elected Mayor of Cork, Terence MacSwinney, inside a British prison while on hunger strike in 1920 (also footage of his funeral), and of Michael Collins (and other leaders) before and during the Civil War.

Using rare archive sequences like these, ONE ISLAND, TWO IRELANDS sets the "troubles" in their historical context, looking at the religious and cultural differences, the nationalists' aims, the democratic solutions attempted and the violent traditions of the paramilitary groups.