Celebrating the end of exams with best friend Grace, 17 year-old Alex rescues a swan caught on a wire in the Thames mud and finds an extraordinary bracelet. Through its disturbing and compelling powers, she finds Callum, a soul locked in a half-life of sadness and mystery following a terrible accident, and his persuasive and sinister sister, Catherine. As Alex and Callum grow closer despite the enormous obstacles to their love, the dangers mount until they must risk everything.