A boy named Jeb finds the half-decomposed carcass of a mysterious animal washed up on a Nantucket beach. Not exactly a dog, not a cat, with the hands of a raccoon, no one's seen anything quite like it before. Until the creatures start turning up, alive and well, in isolated pockets across Massachusetts and upstate New York... adopting some people and slaughtering others. A tech billionaire forms an alliance with a clandestine government agency...