Bill Chrushank (Jeff Fahey) is a criminal psychologist who loses his arm and nearly his life in a grisly car accident. A daring medical operation follows in which a donor's arm is successfully grafted onto Bill's body. But after the operation, the arm starts to take on a violent life of its own, striking out against Bill's wife and children. Consumed by fears about his dangerous behavior. Bill is driven to learn the donor's identity -- a horrifying discovery that delivers him into a world of unimaginable terror.