Small Blue Thing (Small Blue Thing Trilogy)

When 17 year-old Alex rescues a swan caught on a wire stuck deep in the Thames mud, she finds an extraordinary bracelet. Through its disturbing and compelling powers, she meets 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 Alex must risk everything to save her best friend and Callum must risk everything to save Alex.