The discovery of a mysterious dinner service in a Welsh attic triggers a dangerous, cyclical reenactment of an ancient, tragic legend. Alison, her step-brother Roger, and a local boy named Gwyn find themselves unwillingly cast into the roles of figures from the Mabinogion, a cycle of Welsh myths. As the supernatural influence of the legend begins to override their own identities, the three teenagers must navigate the mounting pressure of inherited jealousies and the physical manifestations of the myth. The narrative unfolds through a tense, atmospheric lens, focusing on the psychological erosion caused by the past encroaching upon the present.

This work is widely recognized as a significant contribution to twentieth-century fantasy, noted for its sophisticated blending of myth and realism. Critics often highlight the author's ability to maintain high narrative tension while exploring complex emotional landscapes. Readers frequently observe that the story avoids simple resolutions, instead favoring a darker, more ambiguous exploration of its central themes. The book remains a staple in discussions regarding the evolution of fantasy literature for younger audiences, consistently praised for its structural precision and thematic depth.