Dr. Eric Mason (Nicol Williamson), a noted psychologist specializing in mind control, uses his expertise to carry out the slaying of his best friend and primary assistant, Dr. Charles Hunter, with the help of his two pet Doberman pinschers. As Lt. Columbo tries to discover why two seemingly lovable Dobermans would, without reason, attack someone they knew, he engages in a head game of his own to expose Dr. Mason before the dogs are put to sleep.