Young people in Santa Feliz have started to change shape, transforming from human to wild animal and back again. When this happens to Josh Saunders, he keeps it from all but his two best friends, and tries to resume a normal life. But an encounter with another Wildling and the accidental betrayal of his secret force Josh's friends to intervene. They must grudgingly put their trust in others, including other Wildlingsand, most challenging, in each other if they ever hope to save him.