Superman ends up on a planet under a red sun and loses his superpowers. A caveman strikes him down and steals the Superman suit -- Superman, who was once the strongest man alive, is now the weakest! Eventually, Superman is rescued by his friends Jimmy Olsen and Lois Lane, who have arrived from Earth in a spaceship.
Mr. Mxyzptlk from the 5th dimension stops by briefly to curse Superman: everything he says becomes a reality -- literally! Soon, Superman is afraid to even open his mouth, but the curse is lifted when Superman says his own name backwards.