After an unusual meteor shower leaves most of the human population blind, a merchant navy officer must find a way to conquer tall, aggressive plants which are feeding on people and animals.

A strange meteor lands in Japan and unleashes hundreds of insect-like "Legion" creatures bent on colonizing the Earth. When the military fails to control the situation, Gamera shows up to deal with the ever-evolving space adversary. However the battle may result in Gamera losing his bond with both Asagi and humanity.

As Zac’s relationship with his long suffering girlfriend deteriorates, a mysterious ‘plant’ is discovered in his back yard.