Dr. David Banner (Bill Bixby) has repressed the monster inside him for nearly two years and is close to curing himself of the Hulk (Lou Ferrigno) with the development of a Gamma Transponder.
As he nears the end of his research, Banner becomes reacquainted with his former colleague Dr. Donald Blake (Steve Levitt), who has possession of a mystical hammer capable of summoning Thor (Eric Kramer), an ancient Viking warrior from Asgard. Learning the potential of the Gamma Transponder, a group of criminals kidnap Banner's girlfriend to gain possession of the device, leading Hulk and Thor to team up and foil their plans.