 His "An Isild a-heul", or "Yseulte seconde" (1963), was a three-act tragedy based on the story of Tristan and Isolde, but with a focus on Tristan's wife rather than his lover.While written in Breton, it was published in a dual text, with a French translation on the facing page, and was broadcast on the France Culture radio station in 1965.Helias's best-known and most often performed play is "Mevel ar Gosker", or 'The Yardman of Kosker'.