As if losing her mother and moving to live with her grandmother in Knob's End weren't enough to contend with, sixteen-year-old Sophie James soon discovers that her new best friend is more than the average high school girl. Nerys is a magical Tylwyth Teg from the land of Annwn, and has been forced to seek refuge from a terrible fate.Unless the people of Annwn can find a way to break the pact made with the sinister Coraniaids some two thousand years before, Nerys and her sisters will be forced into marriage, and their homeland will be changed forever.To save Annwn, Sophie and Nerys need to find the Dagger of Everlasting Truth and destroy it. The problem is no one knows its location, and, with so many lives in mortal danger, there is no time for mistakes.Lies and danger lurk around every corner; yet there persists a rumour of a human girl who may hold the key to their salvation, a girl with the gift of prophecy. Could Sophie be the one?