The microscopic alien life-form Hedorah feeds on Earth's pollution and grows into a poisonous, acid-secreting sea monster. After it sinks an oil tanker and attacks Dr. Toru Yano and his young son Ken Yano, scarring the doctor, Hedorah's toxic existence is revealed to the public. Ken Yano has visions of Godzilla fighting the world's pollution and insists Godzilla will come to humankind's aid against Hedorah.