Ken Kuronuma

In an effort to find an economic means of purifying salt water, a joint U.S.-Japanese military command is set up on an isolated Japanese island where an unusual salt water lake is situated. However, their purifying experiments arouse the prehistoric monster Obaki from hibernation at the lake's bottom, and it proceeds to attack Japan. Although made by a U.S. independent film company, this film was based on a Japanese Toho monster film of 1958, "Daikaiju Varan", from which all of the monster effects scenes and a few incidental dramatic shots were edited into it.

When a rare species of butterfly is found in a mysterious valley in Japan, a pair of entomologists go to investigate and find more. They discover Varan, a giant monster, Who decided to leave the valley and head straight for Tokyo.

九州の阿蘇山にある炭坑で、坑道に巣くう巨大なヤゴ・メガヌロンの幼虫による犠牲者が発生した。事件を調査する河村は、その怪物をもしのぐ、巨大な怪鳥の姿を目撃する。その怪鳥・ラドンこそ、各地で相次ぐ災害の元凶だったのだ。その音速を超える飛翔速度はソニックブームを起こし、街はまたたくまに壊滅していく。そして、自衛隊の圧倒的な火力によってラドンを追いつめたかに思われたとき、もう一体のラドンが現れたのだった……。