Two pilots named Tsukioka and Kobayashi are hunting for schools of fish for a tuna cannery company in Osaka. Kobayashi's plane malfunctions and is forced to land near Iwato Island, an uninhabited strip of rocks formed by volcanic eruptions. Tsukioka then looks for Kobayashi and finds him safe, with only a wrist sprain. While talking, the two men hear some strange sounds and find two monsters fighting. Tsukioka immediately recognizes one of the monsters to be Godzilla. The two monsters then fall off a cliff, into the ocean.
Tsukioka and Kobayashi report to the authorities in Osaka, and find out that the other creature, Godzilla was fighting Anguirus. A group of scientists with the two pilots researched Anguirus in a book written by a Polish scientist. Anguirus and Godzilla lived around the same time millions of years ago. Anguirus hated hostile creatures, which explains the intense rivalry between Anguirus and Godzilla.
Dr. Yamane, who experienced Godzilla's first attack, was also present at the meeting, and shows a film of Godzilla attacking Tokyo just one year before. He then explains that the monster Tsukioka and Kobayashi saw is another Godzilla. Yamane states that there is no way to kill Godzilla, and that Dr. Serizawa, the inventor of the weapon used to kill the previous Godzilla, the Oxygen Destroyer, had died and burned the formula. Yamane, though, suggests that the military should use flares on Godzilla to attract the monster away from the shore. Godzilla becomes angry when he sees lights because the hydrogen bomb's bright explosion had awakened him.
One day unexpectedly, Godzilla shows up on the shore of Osaka. Jets are sent to shoot flares from their planes to lead Godzilla away from the shore. Godzilla sees the flames, and, as Yamane predicted, starts to walk away.
Meanwhile, a prison truck transports dangerous criminals to another part of the country. All of the criminals, using body language, decided that this would be a great opportunity to escape from prison. The prisoners beat up the two policemen guarding the back door of the truck, and run away. A few of them find a gasoline truck, and put the petal to the metal. The truck crashes into an industrial building and starts a massive fire.
The fire attracts Godzilla to the shore of Osaka again. A few minutes later, Anglilas swims to shore and attacks Godzilla. The two creatures fight an intense battle, while destroying several buildings, including the tuna cannery that Tsukioka and Kobayashi work for. Godzilla finally bites Anguirus's neck, and throws him on a moat near Osaka Castle. Godzilla then fires his atomic ray, and burns Anguirus to death.
Tsukioka and Kobayashi are transferred to a Hokkaido plant. During a company party, Tsukioka and Kobayashi are notified that Godzilla destroyed one of the company fishing boats. The military, and Tsukioka begin a massive search for Godzilla. Tsukioka spots Godzilla swimming to the shore of a small, icy island. He notifies the cannery, and Kobayashi takes off in his plane to switch shifts with Tsukioka.
Kobayashi dives his plane towards Godzilla to distract him from walking back into the ocean. Tsukioka then transferred to the air force, travels on a jet with an old college friend. They drop bombs on Godzilla but are unsuccessful. Godzilla then wades towards shore. Koboyashi dives towards Godzilla again but Godzilla fires his atomic ray on Kobayashi's plane. The plane then crashes on an icy mountain, killing Kobayashi.
Tsukioka grieves but then notices that the military can shoot missiles at the mountain, and bury Godzilla in an avalanche. The jets fire the missiles, and bury Godzilla in snow to his waist.
The jets return to base to reload, and Tsukioka is authorized to fly in his own jet. The jets return to the icy island, and shoot missiles at the mountain, burying Godzilla to his neck. Tsukioka then shoots his missiles burying Godzilla completely. Tsukioka looks to the sky, and says, "Kobayashi, we buried Godzilla for you."
The film sold approximately 8,340,000 tickets in Japan. It is the third most-attended Godzilla film in Japan. However, the film was poorly received by fans and critics, and Godzilla would not re-appear until 1962 in King Kong vs. Godzilla.
U.S. releaseA project called The Volcano Monsters was planned for 1957 after Henry Rybnick and Edward Barrison acquired the rights to Godzilla Raids Again. The film was to be altered and the monsters reduced to dinosaurs. In addition, all scenes with Japanese actors and Godzilla breathing fire were to be cut. Toho, however, was willing to peddle their films in the United States and sent the suits for Godzilla and Anguirus to be used in new footage. Ultimately, the modified film was never produced, and the monster suits disappeared.
In 1959 Warner Brothers theatrically released a heavily edited version of the film, under the title Gigantis the Fire Monster. For a long time, this change in name was thought to be because Warner did not have the rights to "Godzilla". However, Paul Schreibman, the producer of the American version, said that he changed Godzilla's name to "Gigantis" to give the audience the impression that they were seeing a new monster. He has since regretted that decision.
On November 7th, 2006, Classic Media, after releasing both the Japanese and American version of Gojira in a 2-disc DVD two months previous, released both the Japanese version and American version of Godzilla Raids Again. Prior to this release, the film had been unavailable on North American home video since Video Treasures' VHS release in the early 90s. A notable difference between the original "Gigantis" and the U.S. version featured on this DVD, is the fact the "Gigantis" title card has been replaced with a newer "Godzilla Raids Again" one, by request of Toho.In the americanized version, some of Angurius roar was mixed in with Godzilla's to make it seem as though they were related, as the movie states. While the original version uses silence to create tension, the American version features an extreme case of "over-narration", with every action and thought being described in detail by the film's main protagonist, Tsukioka (dubbed by George Tekei). This smothering narration, along with the scattered plot, poor dubbing, and the stock "B-movie" music that replaced Masaru Sato's original score make Gigantis the Fire Monster one the best examples of the poor Americanization of the series.
- The Godzilla suit used for this film has been nicknamed "GyakushuGoji". It was slimmer than the previous suit, making any scenes with Anguirus easier.
- In the American version of Godzilla Raids Again, Tsukioka is dubbed by the voice of George Takei, before he became famous for the role of Mr. Sulu on Star Trek. Kobayashi is dubbed by Daws Butler, who would later voice Yogi Bear & Cap'n Crunch! (Anyone who has seen the film can easily recognize Yogi Bear's voice, although with a faked Japanese accent, comming from Kobayashi.) As author David Kalat said of the American version, "With Mr. Sulu and Yogi Bear as the lead characters, it is...hard to take the proceedings seriously."
- Minoru Chiaki, who plays Kobayashi in this film, had previously stared in Akira Kurosawa's The Hidden Fortress, and it is said that his role in that film inspired the charactar of C-3P0 in George Lucas' Star Wars (1977).
- The J.S.D.F.'s tactic of enforcing a blackout in Osaka to protect it from Godzilla is the same tactic used by Japan durring WWII to protect cities from Allied bombing raids.
- In the american version, Godzilla's roar was altered to sound like Anguirus' roar, for an unknown reason.
- This is the only Godzilla film to date where Godzilla's back plates do not glow prior to releasing his heat ray.
- Takashi Shimura (Dr. Yamane) and Minoru Chiaki (Kobayashi) had previously starred together in Akira Kurosawa's famous film Seven Samurai as two of the title characters. Coincidently, Minoru Chiaki's characters in both films perish.
- This is the only time where the JSDF wins out over Godzilla with a co-ordinated tactical strike, and with no aid from another monster or some sophisticated form of technology.
- In contrast to the first film, which was so serious that depicted very little smiling and no laughter from its primary characters, the characters in this film are more lively and partake in numerous moments of laughter.
- There are no scenes which feature Godzilla using his heat ray from the full suit view. Every time he does, the hand operated puppet head is used. This is do to the GyakushuGoji suit's mouth being unable to open wide enough to mimic the release of his atomic breath.
- Unlike later designs of Anguirus, his spike-covered shell in this movie has a rectangular shape and appears to be somewhat flat. Designs for the suits from his next appearance to date have more circular and humped shape to his shell.
- This is the first Godzilla movie to have two monsters.