Astronauts Glenn and Fuji investigate Planet X and encounter mysterious aliens known as the Xiliens, who ask Earth's people to help save their world from "Monster Zero". In exchange for borrowing Godzilla and Rodan, the Xiliens offer a cure for cancer. As Glenn investigates, he develops a romance with Miss Namikawa and uncovers the Xilien's true intentions.

• TOHO
• United Productions of America
• Nick Adams
• Akira Takarada
• Keiko Sawai
• Kumi Mizuno
• Jun Tazaki
• Akira Kubo
• Yoshio Tsuchiya
• Takamaru Sasaki