In 1904 Lady Augusta Gregory published the book that, together with her Cuchulain of Muirthemne, W. B. Yeats called the finest work to come out of Ireland in his lifetime. She had sat for years in the kitchens of Kiltartan in Galway, listening to the old Irish-speaking tellers recount the stories of Finn and Oisin and the Fianna as they had always been told at the fireside. She then went back to the medieval manuscripts where the same stories had been set down by monks a thousand years earlier. She wove the two traditions together and rendered them in an English that kept the rhythm of the Irish sentence behind it.

The result is this book. Part One is the Gods: the Tuatha De Danaan arriving in Ireland in a mist, the coming of Lugh of the Long Hand, the sons of Tuireann paying an impossible ransom, the great battle of Magh Tuireadh, the coming of the Gael, and the Ever-Living Ones, Bodb Dearg, the Dagda, Angus Og, the Morrigu, Manannan, and the tragic fate of the Children of Lir. Part Two is the Fianna: Finn, son of Cumhal, and his household, the battle of the White Strand, the great pursuit of Diarmuid and Grania, the wearing away of the Fianna, and at the last, Oisin returning from the Country of the Young to argue with Saint Patrick about heaven and hell.

Gregory's Dedication, Yeats's famous preface, and Gregory's own notes, pronunciation guide, and list of place-names are all preserved. An introduction by Lucy McDonnell places her achievement in context for the modern reader.