Dr. Roger Girard is a rich scientist conducting experiments on head transplantation. His caretaker has a son, Danny, who, although fully grown, has the mind of child. One day an escaped psycho-killer invades Girard's home, killing Danny's father before being gunned down himself. With the maniac dying and Danny deeply unsettled by his father's death, Dr. Girard decides to take the final step and transplant the killer's head onto Danny's body.

An outlaw motorcycle gang is headed by two couples (Bambi Allan, Jennifer Bishop, Bill Bonner and Bryan West). The gang is badly hurt by a botched robbery and the four stars, the only survivors, eventually head to Mexico, where they have to combat a gang run by a sadistic Mexican (Rafael Campos).