Comments: Exeter, an alien from the planet Metaluna invites some of America's most brilliant minds to work on a top-secret project at his earthly mansion. Among those accepting the invitation are Cal Meacham and his ex-fiancee, Ruth Adams. Torn between his duty and his morals, Exeter whisks Cal and Ruth away in his flying spaceship back to his home planet. Cal and Ruth learn Exeter's true motives - to use the scientist's atomic knowledge in building a defense shield to protect Exeter's war-ravaged planet against their enemy, the Zahgon. Only shortly after they land, Cal discovers that the ruler of Metaluna plans to invade Earth and brainwash the population. Alone on an alien world, Cal and Ruth run for Exeter's ship to make an escape but are attacked by the hideous Metaluna Mutant.
Filmed completely in a revolutionary new format called TECHNICOLOR, featuring "This Island Earth" was considered one of the most ambitious science fiction films of its era.