Godzilla begins off the shores of post-World War II Japan. Freight ships, fishing boats, and salvage vessels are mysteriously destroyed near the Odo Island, with very few survivors. Fishing villages begin wasting away when all of their efforts to produce a regular catch become futile. Village elders blame a prehistoric sea creature known as “Godzilla” for all of the incidents.
As news reporters investigate these claims on the Odo Island, a ritualistic dance is performed to appease the never before seen “Godzilla.” After the event, a storm ravages the island, destroys the fishing village, and kills nine people along with all of their livestock.
The Japanese government commissions a paleontologist, Kyohei Yamane, to investigate the island incident. Shortly after, Yamane discovers gigantic radioactive footprints; the fishing village is visited by the dinosaur like creature that created these prints. Yamane estimates this Godzilla is an ancient, 50 meters tall, sea creature that has evolved and became terrestrial after being disturbed by underwater hydrogen bomb testing.
While the government attempts to kill Godzilla, Yamane pleads his case to have the creature studied, believing it is immortal, having survived all of the H-bomb testing. Little does Yamane know, his colleague, Daisuke Serizawa, is secretly working on a chemical weapon he believes can destroy Godzilla.
Godzilla begins to repeatedly walk its way into Tokyo, destroying homes, commuter trains, and the Tokyo Tower, causing a large number of casualties. After all of this destruction, Serizawa is convinced by Yamane’s daughter, and Serizawa’s potential bride, Emiko, to use his weapon on Godzilla to prevent the further loss of life.
Serizawa engages his weapon in the Tokyo Bay, successfully neutralizing Godzilla. Although this seems like a victory for the Japanese people and the rest of the world, Yamane is still convinced Godzilla will return, as long as man continues to toy with nature while creating nuclear weapons.