Nineteen sixty-eight, the French government heard about the Americans developing a thermonuclear bomb test for something and decided to develope their own nuclear bomb incase of another world war again
They test it on an island in the French Polynesia.
Unknowingly, they expose an iguana nest to radioactive fallout.
Three years later it's nineteen seventy-one.
Godzilla grew from a hundred and ninety-six feet to two hundred twenty-nine feet.
Godzilla and Mothra have been making every monster they come across, know they are the King and Queen of all the monsters and take down any monster that threaten humans.
Monarch started building a profile on Godzilla and Mothra and monsters they battled and won.
Humans were sworn to remain quiet about monsters, so people don't live in fear of giant monsters.
In Suruga, Japan, young Ken Yano is playing outside with his Godzilla toys when his uncle Yukio Keuchi ask him "is Godzilla your idol?"
Ken replies "yes, Godzilla is like superman."
A local fisherman, Gohei comes to Yano's house to show Ken's biologist father, Toru Yano, a strange black tadpole he found.
Dr. Yano research the specimen and is unable to identify the specimen and ask "where did you catch it?"
Gohei replies "I caught it in Suruga Bay, which is becoming more polluted by the day."
Later in the day, the family is watching the news and hear a report about an accident in Suruga Bay where a huge black monster attack two oil tankers, which had crashed.
Ken immediately recognizes the monster as a large version of the tadpole Gohei had brought over.
Dr. Yano decides to go investigate Suruga Bay and puts on a diving suit.
Ken stayed behind on the rocks and wait for his father to return.
As Yano swims beneath Suruga Bay, he finds the sea floor polluted with all manner of garbage and several dead waterfowl.
Ken sees the huge monster tadpole from the television approach him.
The creature leaps at Ken, who defends himself with a knife.
The knife slices through the monster harmlessly.
The monster lands back in the water and swims towards Dr. Yano's location.
Ken is alright except for the burn on his hand.
Beneath the water, Yano sees the tadpole monster coming after him and hides.
The creature attacks Dr. Yano.
Following the attack, Dr. Yano is confined to bed rest with gruesome burns on his face.
Reporters interview him and Ken about their encounter with the monster, which Ken decides to name it Hedorah.
Ken tells the reporters "Hedorah comes from the sludge dumped into the sea and feeds on pollution. There is more than one Hedorah."
Dr. Yano adds "Hedorah is dangerous to burn by contact" showing his burned face.
Reporters prepare to take pictures of Dr. Yano's burned face, but his wife, Toshie ask them not to.
Yano tells her "people should know what the threat is concerning Hedorah."
Ken tells the reporters "you can take pictures of my hand."
Over the following days, numerous accidents occur involving tankers by Hedorah.
Ken looks at his Godzilla toy and says "we need your help, Godzilla."
Two Shobijin girls riding Fairy hear the boy's plea and fly back to Infant Island to inform Godzilla and Mothra about the boy needing help.
Once the Shobijin returned, Mothra chirped with a red glow around her body "where did you two go?"
The Shobijin reply "we went to check on Japan and saw this little boy playing with his Godzilla toy and he said that they need Godzilla's help with something."
Godzilla growls "they need my help?"
Shobijin nod their heads "yes."
Godzilla roar at Mothra "you up for another battle?"
Mothra chirps "yes and it sounds like my King has a worshiper."
Godzilla roars "Shobijin, bring this boy to the bay."
The Shobijin leave the King and Queen's room and head back to Suruga to tell the boy.
Night time came, Yano family was sitting down eating dinner, when there is a knock on their door.
Toru goes answer the door to see no one.
The Shobijin smiles "down here."
Toru looks down to see two twin girls and a moth and brings them inside and sets them in the middle of the table.
Toshie ask "who are you two?"
The Shobijin reply "we come as a messengers."
Toru ask "as messengers? By who?"
The Shobijin reply "by the King and Queen of all the monsters, Godzilla and Mothra."
Dr. Yano ask "are they coming to help?"
The Shobijin smiles "yes, we told them that Japan needed their help on your son's request and they will be in the bay in the morning and we are to bring you to the bay to meet them."
Next morning, JSDF started evacuating the city of Suruga while sounding the emergency alarm.
Dr. Yano was studying the Hedorah that Gohei brought him, but finds that it dried out and begun to crumble.
He finds that the tadpole is actually a mineral.
He placed powder from the Hedorah in water, where it forms into very small Hedorahs.
He placed them in dirty water and they combine into a large Hedorah.
Yukio attends a nightclub where his girlfriend, Miki Fujinomiya is performing.
Hedorah evolves into a terrestrial Landing Stage and crawls onto land in the port area.
Godzilla rest his head on the beach with Mothra laying on his neck.
Ken starts explaining the situation "the pollution in this bay has mutated a mineral into a dangerous creature that burns on contact."
JSDF soldiers were tensed at Godzilla being near the city.
Hedorah heads over to a nearby factory and breathes in the toxic pollutants and grows bigger from ninety-eight feet to hundred and ninety-six feet but short to Godzilla's two hundred and twenty-nine feet.
Godzilla has Mothra blast Hedorah with her energy beams while Godzilla fires his atomic fire beam at Hedorah.
Hedorah leaps at Godzilla to cover him, but he tears Hedorah off.
Godzilla throws him in the air.
A piece of Hedorah broke off into the upstairs of the nightclub.
They battle before Hedorah flees into the ocean.
Godzilla and Mothra stare as Hedorah disappear in the ocean.
Dr. Yano hears his brothertell him about Hedorah site and has his family harvest many samples of ash.
Yano tested Hedorah's biology and uncover it's secret "the creature is composed of undiscovered element that I call Hedrium. Hedrium absorbs tocins and pollutants which are converted into energy for Hedorah."
Miki ask "would this solve our pollution problem?"
Yano replies "no, it will make it far worse. Hedrium reacts with pollutants, producing deadly sulfuric acid that burns on contact. I believe Hedorah is an alien that came to Earth on a comet, probably a dark, sticky planet."
Next day, Godzilla and Mothra patrol the city border.
Miki and Yukio took Ken to an amusement park.
Ken rode a roller coaster where he sees Godzilla comes to the amusement park causing people to panic.
Ken runs to him to see what he is doing here.
Godzilla bends down and picks ken up and growls softly at him.
One of the Shobijin girls translates "Hedorah is attacking the city again. I need you to get people below the city."
Godzilla sets Ken down and watches as Ken gets people to go below the city.
Hedorah attacks Fuji City before Godzilla and Mothra engage in battle.
Soon Hedorah takes flight and spraying sulfuric acid mist directly in Godzilla's face.
Godzilla falls to the ground gasping for air.
Mothra fires her energy beams at Hedorah.
Hedorah sprays mist over fleeing crowd, reducing them to skeletons in moments.
Hedorah disappear in the ocean.
Fuji City is enveloped in toxic smog.
Godzilla roars at Hedorah's retreating form.
People that listen to Ken survived Hedorah's attack.
Toru worked on defeating Hedorah.
Ken ask "could you dry Hedorah out if he's made of sludge?"
Yano widened his eyes and placed Hedorah in between two electrode panels, a method to dry fields in Hokkaido.
He activates it and dries out Hedorah in moments.
Yano contacts the JSDF to make electrodes on a larger scale.
Ken decided to join the party at mount Fuji that his uncle was throwing.
A man approaches young Ken and ask "your the boy who has a connection with the King of monsters?"
Ken smiles "I'm a fan of him."
The man ask "do you think Godzilla can beat Hedorah?"
Ken smiles "he and Mothra have beat every monster they come across."
Yukio ask "nephew, I don't think Godzilla and Mothra can beat a sulfuric acid monster."
Ken smirks "you want to bet twenty dollars?"
Miki sighs "Yukio, stop shooting down our nephew's hero. When we have kids, you better not be crushing our child's hopes."
Next they hear roars of Godzilla and Hedorah along with Mothra.
Godzilla fires his atomic fire beam, only it's red instead of blue.
He unleashed a nuclear pulse at Hedorah.
Mothra fires her energy beams at Hedorah.
Miki curious says "they must have juiced up on nuclear energy."
Hedorah fires his Hedrium Light Ray, knocking Godzilla down.
Mothra knocks Hedorah down.
Godzilla unleashes a nuclear pulse at Hedorah, burning him.
Hedorah goes to fly away before Godzilla grabs him and fires his atomic fire beam inside Hedorah's mouth burning him on the inside.
Hedorah falls down dead.
After Hedorah is no more, Godzilla and Mothra leave going home.
Ken calls to Godzilla, to which Mothra chirps at him.
Godzilla stops walking to see Ken one last time.
Ken smiles "your the best no matter what people think of you" and hugs his leg.
Godzilla and Mothra return to Infant Island to rest.
Mothra nuzzled Godzilla before the two went to sleep.