As alien invaders plot to conquer the Earth, two Boy Scouts steal a mini-submarine and discover Gamera in their midst. Transported to the alien's spaceship, the Scouts are menaced by the evil inhabitants, including Viras, a squid-like monster that grows to colossal size to battle Gamera.

• Daiei Film
• Kōjirō Hongō
• Tôru Takatsuka
• Carl Craig
• Michiko Yaegaki
• Peter Williams
• Kōji Fujiyama
• Mari Atsumi
• Junko Yashiro