The Romance of Ydersurvives in a unique manuscript in Cambridge University Library, and has only once been edited; no translation survives. Yet it is a highly interesting work, reflecting a tradition which reaches back to the beginnings of Arthurian romance in the early 12th century; it is linked to the famous Arthurian sculpture on the cathedral at Modena, and contains an episode which foreshadows the temptation scene in Sir Gawain and the GreenKnight, while elsewhere Celtic material is much in evidence as the basis of the tale. It is also close in style and sometimes in content to the work of Chretien de Troyes. Dr Adams' text provides a clear version of an often corrupt original, and the facing translation serves to illuminate the text further, enabling this neglected work to take its rightful place in the ranks of Arthurian literature.