A mysterious meteor shower occurs above a field in Cornwall, and a team of scientists led by Dr. Curtis Temple (Robert Hutton) is sent in to investigate. The scientists and local bystanders soon find themselves possessed by an alien force which wants to enslave them. No one is immune from the invasion except for Dr. Temple, who is shielded from the meteor's influence by a metal plate that was inserted to protect his skull after a recent accident. He discovers that an alien race on the moon seeks to use the manipulated scientists for secret purposes. But, as Temple learns more about the invaders, he realises that they may not be as evil as he once thought.