The film begins with a team of United Nations astronauts planning an upcoming moon mission. The astronauts are both confused and intrigued by a man who claims he, his fiancée and a scientist journeyed to the moon 65 years ago and were attacked by "Selenites," grotesque, human-like ant-forms that live in immense crystal caverns. Now it's up to the U.N. team to attempt a lunar landing that could be more horrifying than ever believed possible.