Based loosely on the Irish myth The Wooing of Etain, the story follows the love of a mortal king, Eochaidh for an immortal fairy woman Etain who at the end of a year with him is reclaimed by her immortal lover, Midir. Woven throughout is the enigmatic and dark fairy fool, Dalua, who stands on the threshold between the worlds. This critical edition of The Immortal Hour contains an introductory essay with a biography of the author, analysis of the play and the history of its success as an opera. The text of the play itself is fully annotated with the references to Celtic mythology and a comparison to an earlier publication of it.