John Whitney (Lewis Van Bergen), an anthropologist for the Museum of Natural History in Chicago, is studying a newly discovered tribe in South America, and drinks a soup made for him by the tribesmen. A short time later, he is seen accosting the captain of a merchant ship, asking that the shipment he has sent back to Chicago be unloaded from the ship. When the captain informs him that it's too late because the ship is about to leave, Whitney sneaks aboard. As the ship leaves the dock, Whitney searches through the cargo hold for his crates, crying out in despair when he does not find what he's looking for.
Five Michigan State University students, Ash Williams (Bruce Campbell) and his girlfriend Linda (Betsy Baker), accompanied by Ash's sister Cheryl (Ellen Sandweiss), their friend Scotty, and his girlfriend Shelly , venture into the Tennessee hills to vacation in an isolated cabin for their spring break. They soon run into trouble, first narrowly avoiding another motorist, then having a sudden scare as the bridge near the cabin begins to collapse as they cross. That night, while Cheryl is making a drawing of a clock, her hand becomes violently possessed by a mysterious entity, causing her to draw a picture that looks like a deformed, evil face. She fails to mention the incident to the others, dismissing it as her imagination.
Godzilla is a literal force of nature to Japan. The Godzilla Prediction Network (GPN) functions independently to study the monster and predict its landfalls. Meanwhile, the scientists of Crisis Control Intelligence (CCI) find a sixty million year old UFO deep in the Japan Trench. As CCI attempts to raise the UFO to study it, it takes off into the sky on its own. Godzilla arrives and battles the Japan Self Defense Forces, now equipped with powerful Full Metal Missiles, but the UFO appears, searching for genetic information that only Godzilla possesses. It defeats Godzilla, driving the monster underwater, and then lands to replenish its solar power.
Godzilla cells brought into space by Biollante and Mothra are exposed to intense radiation from a black hole. The celestial fission creates a highly aggressive extraterrestrial beast closely resembling Godzilla. This "SpaceGodzilla" quickly makes its way to Earth.
In 1993, an asteroid lands in the ocean and awakens Godzilla. The next day, a young man named Takuya Fujita is detained after stealing an ancient artifact. Later, a representative of the Japanese Prime Minister arrives with Takuya's ex-wife, Masako Tezuka, and offers him to explore an island with Masako and Marutomo company secretary, Kenji Ando, and become a free man. Takuya initially turns down the offer, on the basis that he is to be released in another week. But after his ex-wife informs him that his sentence has been reconsidered, he accepts. After the trio arrives at the island, they find a cave behind a waterfall. Inside, they discover ancient paintings, including a picture of two giant insects fighting one another. While studying them, the sun shines through a hole in the wall, and the light points to a small opening in the cave, where they come upon a giant egg. The three hear a pair of voices, which belong to the Cosmos. They keep the earth's natural order in balance, and informs them the egg belongs to Mothra.
During a meeting of the Japan Self-Defense Forces (JSDF) for the potential return of Godzilla, Admiral Taizo Tachibana briefs cadets about Godzilla's first attack. A nuclear submarine is reported missing, which is later found to have been destroyed by Godzilla. Tachibana's daughter, Yuri Tachibana films a docudrama with her crew at Mt. Myoko, where a mysterious earthquake randomly ensues. The odd earthquake returns later that night burying a biker gang and leaving one surviving trucker who witnesses the monster, Baragon.
A small team of oil rig workers are searching for undiscovered oil at the oil rig Sector 7, off the coast of Jeju Island. After the tension builds from countless failures, the main character Hae-joon's uncle returns with the hope of finding the untapped wells of oil. What they don't realize is that he has a much different motive. Working together with a researcher on board the rig, he plans to breed a newly discovered life-form whose bodily fluids can burn for longer than 30 hours, as a new form of fuel instead of oil.
In 1992, the United Nations establishes the United Nations Godzilla Countermeasures Center (UNGCC) to stop Godzilla. The remains of Mecha-King Ghidorah are salvaged from the ocean and used to create two anti-Godzilla machines. The first is a flying gunship called Garuda. The second and more powerful machine, modeled after Godzilla itself, is called Mechagodzilla.
In 1996, after the death of SpaceGodzilla, Miki Saegusa travels to Birth Island to check on Godzilla and its adopted child, but finds the entire island destroyed. Godzilla appears in Hong Kong, covered in glowing lava-like rashes. It goes on a rampage, causing major collateral damage and killing thousands of civilians. A group of representatives from the Japan Self Defense Forces (JSDF) hires college student Kenichi Yamane, the grandson of Dr. Kyohei Yamane, to work at the center in an attempt to unravel the mystery of Godzilla's condition. Yamane suspects that Godzilla's heart, which acts as a nuclear reactor, is going through a nuclear meltdown. He theorizes that, when Godzilla's temperature reaches 1,200 degrees Celsius, it will explode with a force approximately "1,000 times greater than all nuclear weapons put together, a burst of power unseen since time began.
A ship carrying plutonium collides with a floating atoll off the eastern coast of the Philippines, one of many incidents occurring throughout the area. As the anomalous formation approaches Japan, a team of scientists led by Naoya Kusanagi (Akira Onodera) discover orihalcum amulets and a stone slab covered in Etrurian runes on the atoll. During the investigation, the atoll suddenly quakes, destroying the slab and throwing the scientists into the ocean. One member of the team, Marine Officer Yoshinari Yonemori (Tsuyoshi Ihara), sees the eye and tusk of a giant turtle.
In 1999, 45 years after Godzilla's first attack, Lieutenant Akane Yashiro, a mazer-cannon technician, is unable to kill a new member of Godzilla's species during her first fight. She is made a scapegoat for the military's losses during the battle and transferred to a desk job. During the battle, it was discovered that Godzilla is immune to mazer fire, rendering all of the Japanese military useless against it should it return. Scientists, including single father Tokumitsu Yuhara, are gathered to build a bio-mechanical robot from the original Godzilla's skeleton. Four years later, the cyborg Mechagodzilla, named Kiryu, is finished and inducted into the Japan Self-Defense Forces along with its human pilots as the Kiryu Squadron. Akane becomes the main pilot for Kiryu. However, memories of Akane's actions during the original fight still linger, and one of her squadron mates, Second Lieutenant Susumu Hayama holds her responsible for the death of his brother.
The central plot of the film revolves around the titular spider invasion, which occurs when what appears to be a meteorite crashes down in rural Wisconsin, and spawns spiders of varying sizes.
Three years have passed since Gamera defeated the Legion, and the world is once again plagued by the Gyaos, which have evolved into Hyper Gyaos. Mayumi Nagamine, noted ornithologist, returns to aid the Japanese government in addressing this threat. A graveyard of Gamera fossils is found at the bottom of the sea. Shadowy government agents, occultist Miss Asukura and Kurata Shinji, are meanwhile working to a different agenda, with Asukura believing Gamera to be an evil spirit.
A year has passed since the battle between Gamera and the Gyaos, and Japan has struggled to rebuild its cities in the meantime. The military has kept a cautious vigil on the nation's coast, but so far Gamera has yet to return. Suddenly, a series of bizarre incidents reveal a new threat to the land of the rising sun. On a moonlit stroll, science instructor Midori Honami watches as a huge meteor plunges into the mountain snow. The next night, two security guards are horrified as they see large insect-like creatures stealing glass bottles from a nearby warehouse. Soon after, the entire city of Sapporo is covered with strange plants and the link between these events soon becomes clear.
Mr. Tako, head of Pacific Pharmaceuticals, is frustrated with the television shows his company is sponsoring and wants something to boost his ratings. When a doctor tells Tako about a giant monster he discovered on the small Faro Island, Tako believes that it would be a brilliant idea to use the monster to gain publicity. Tako immediately sends two men, Sakurai and Kinsaburo, to find and bring back the monster. Meanwhile, the American submarine Seahawk gets caught in an iceberg. The iceberg collapses, unleashing Godzilla (who, in the Japanese version, had been trapped within since 1955), who then destroys the submarine and a nearby military base.