Majin est de retour pour aider les enfants d'un village dont les pères sont retenus prisonniers comme esclaves du Seigneur Arakawa. Ces derniers fabriquent de la poudre à canon près d'une montagne volcanique d'où s'échappe des vapeurs de soufre.
Alors que Mothra termine paisiblement sa vie à Infant Island en veillant sur son œuf, une compagnie forestière déterre un sceau antique au pouvoir maléfique. La méchante fée Belvera s'en empare et réveille Desghidora...
King Ghidorah attaque Tokyo et enlève les enfants qu'il enferme dans un dôme organique. Mothra tente de l'affronter mais est vite vaincu ; une seule solution émerge : remonter le temps jusqu'au crétacé et tuer King Ghidorah quand il était jeune…
Tout commence environ 16 ans avant le début de l'action principale. C’était le dernier jour de la guerre entre les humains et des monstres géants, les Kaijūs. On dit que ce jour-là, une femme, Margaret, sauva la Terre entière par son courage. C’est aussi le jour où elle rencontra le père de Duncan, Belloc.
Santa (Isamu Yamaguchi) and his friend Koichi (Nagamasa Yamada) are jobless vagabonds. They make their living by picking up coins on streets. Santa has a girlfriend named Omitsu (Yasuko Koizumi), but her father Seizo (Kotaro Sekiguchi) does not like having his daughter date a penniless man. He breaks the lovers up and tries to marry his daughter off to a rich man. Desperate, Santa seeks employment and wanders the streets. He can’t find a job at all but has an inspiration. RKO’s King Kong has been released and is a big hit in Tokyo. He decides to capitalize on its success by dressing up as an ape and playing King Kong in a vaudeville theater! He approaches one theater owner to tell him of the idea and the owner is pleased with Santa’s plan, thus giving him the job. Santa’s King Kong show becomes an instant success, with Santa interacting amongst props on the theater stage in his gorilla suit (small buildings, toy airplanes, a doll etc.). One day while performing on stage, Santa sees that Omitsu and her new rich boyfriend are in the audience. Blinded with rage, Santa jumps down from the stage and runs after them - with his gorilla suit on! Santa creates chaos in the town, as firemen and hunters chase him thinking him an escaped gorilla that is running wild in the streets. Eventually Santa confronts the rich boyfriend and knocks him unconscious. He puts the gorilla suit on him and leaves him lying out cold in the street. Just then Koichi comes and tells Santa that the theater owner will give him a lot of money for his performances. Now that he has wealth, Santa gets married to Omitsu.
Les militaires japonais et américains travaillent ensemble dans le Pacifique sur une île japonaise possédant un lac salé, et tentent une expérience pour désaliniser l'eau. La technique utilisée réveille un monstre préhistorique, Varan, du plus long sommeil jamais observé. Naturellement irrité, le monstre se met en route pour écraser Tōkyō en guise de revanche.
Des chasseurs de trésors capturent un monstre sous-marin, ressemblant à un dinosaure, au large de l'Irlande, et le traînent dans un filet jusqu'à Londres où il est exhibé comme une bête de foire. L'attraction connaît un succès formidable et les spectateurs se bousculent pour découvrir « Gorgo », un monstre de 20 m. Cependant, un scientifique émet une hypothèse qui augure mal de l'avenir : la créature ne serait qu'un bébé qu'un parent beaucoup plus grand pourrait venir chercher…
Daigoro is a monster who was orphaned after the military used intercontinental missiles to kill his mother while she tried to protect him. Only one man stood against that decision. He pitied the infant, and took it as his own and raised him in Japan. But Daigoro grew too large and too expensive to feed. The man made Daigoro an icon for a business. Elsewhere Goliath, a monster who had been trapped in an asteroid for a long time, went to Earth and battled Daigoro. Goliath eventually defeated Daigoro by striking him with lightning from his horn. Goliath then left to pillage the world, leaving Daigoro to die. Daigoro recovered and practiced daily for his next battle against Goliath. After an intense fight, Daigoro breathed his fire ray and managed to defeat Goliath. The humans then grabbed Goliath while he was still weak and strapped him to a rocket and launched him into space.
Intelligent aliens who have been studying Earth for centuries decide to challenge mankind by sending in a 185-foot, laser-eyed monster called Zarkorr to wreak city-crushing havoc. Only one incredibly average young man, postal worker Tommy Ward (Rhys Pugh), can find the beast's weakness and save the planet with the help of a 6-inch-tall pixie (Torie Lynch), who says she is "a mental image projected into his brain" by the aliens. She explains that Zarkorr cannot be destroyed by weapons, but that the key to the monster's destruction lies within the monster itself. Tommy, chosen as an average human, is the one destined to fight Zarkorr, who is programmed to kill him. Tommy asks scientist Dr. Stephanie Martin (De'Prise Grossman) for advice about his mission, but everyone thinks he is crazy. He takes the scientist hostage, but manages to explain his predicament to one of the policemen, who believes him and helps him escape. Dr. Martin agrees to help him. Using computers belonging to a friend of hers, they establish that the monster, which is destroying city after city in the style of Godzilla, neither sleeps nor breathes. Going to the place where the monster first appeared, they come into possession of a strange metallic capsule that fell out of the sky at the time the monster arrived. It is believed to be unopenable, but it opens by itself for Tommy as he touches it. He uses the top of the capsule as a shield, reflecting Zarkorr's laser rays back at him, and the monster dissolves into a small glowing sphere flying into space. Tommy is taken to hospital to recover; a TV reporter congratulates him for saving the world, and he jokes he might run for president.
Une légende datant de plusieurs siècles démontre que les méchants sont toujours punis. Les adversaires sont parfois personnifiés par des gigantesques monstres de l'age préhistorique qui font des ravages considérables lors de leurs combats, et provoquent des destructions semblables à celles d'un tremblement de terre. C'est l'histoire d'un riche et courageux orphelin recherchant le traître qui fomente une rébellion pour assassiner son père, et d'une jeune fille abandonnée à la recherche de sa famille. De nombreux obstacles, dressés par des bandes de truands à la solde des traites, surgissent en travers de leur route provoquant de terribles batailles.
Au cours de la période de Goryeo, un roi dirige le pays d'une main de fer et réduit la population paysanne à la misère et à la famine. Un vieux forgeron sculpte une figurine de monstre à l'aide de grains de riz. Quand elle entre en contact avec le sang de la fille du forgeron, la figurine prend vie et se transforme en monstre de métal géant appelé Pulgasari.