A prison cell that has been sealed for 500 years is opened in the present day and a horrible shape-shifting monster escapes.; Astronaut Lee Crane's space mission is disrupted when his ship goes off course and lands on the planet Zeroz, where he deduces that he is not the first Earthman to visit the planet and that he must uncover the identity of the man who preceded him.; A scientist's neighbor and daughter are shrunk to minuscule size by the scientist's assistant, who plans to steal the shrinking formula for himself.