A group of hostile aliens travel to Earth, seeking to conquer the planet. After their initial ship is destroyed by the giant flying turtle Gamera, they implant a remote control device in the monster's neck, using it to attack Tokyo. Two Boy Scouts, held captive by the aliens, devise a plan to disrupt the device, causing Gamera to wreak havoc on the aliens' own ship instead. However, the turtle soon faces off against the aliens' formidable giant squid leader, Viras.

Gamera vs. Viras
A heroic flying turtle, Gamera, is unwittingly bound to a group of malevolent aliens after a magical curse is cast upon him, but the timely intervention of two courageous youngsters ultimately shatters the spell and sets Gamera free.