All his life, Arawn has heard the stories: how the Clan-lors Cernach drove the Horse-people back to the islands in the Wild Sea, so that all that remained of them were memories and talk - of figures glimpsed by moonlight, of shape-shifters, and of a white horse which runs in darkness; how Roech fell in love with a beautiful princess of the Horse-people, and brought her back to Nam Dubh as his wife; how it brought disgrace on them all, and sent the orphan Arawn and his grandfather into the empty marshlands.

Now, twelve years later, his uncle Mhorged has sent for Arawn and he returns to the stronghold of Nam Dubh. But, set apart from his fellows and suffering all the cruelties and indignities heaped upon him by the vengeful inhabitants, Arawn's sense of isolation deepens - until, at last, he feels compelled to search out his roots with the Horse-people.