Wrongly accused of a crime that he didn't commit, teenager Wil Calloway is sentenced to join the Moon Chase to try to prove his innocence. On the face of it, this sounds easy enough, especially with the help of the huge Fellhounds of Thesk, but as Wil learns more from the mysterious LadyÉlanor and her telepathic sister, Tally, he soon realises that proving his innocence is the least of his challenges - staying alive is another!