 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. Of course, things go horribly wrong and the two-headed creature escapes to terrorize the countryside.