Ocean Beach, a seaside tourist resort, has come under attack by a giant octopus, which captures and devours human swimmers and boaters, picking the skeletons clean of flesh and bone marrow. Marine expert Will Gleason (Bo Hopkins) and crusading newspaper reporter Ned Turner (John Huston) suspect the construction of an underwater tunnel by the Trojan company, owned by Mr. Whitehead (Henry Fonda). Trojan has been using radio signals that have been "above regulated levels", somehow maddening the octopus and causing it to attack human beings. In the end, the octopus is killed by Gleason's pair of killer whales.
A battle for survival begins as a group of mountain hikers in Northern California encounter a chemically imbalanced forest. The recent depletion of the Earth's ozone layer causes the sun to shine powerful ultraviolet light carrying some kind of solar radiation that somehow causes all animals above the altitude of 5,000 feet to run amok and kill, which is very unfortunate for a group of hikers (including Christopher George, Lynda Day George, and Leslie Nielsen) who get dropped off up there by helicopter just before a quarantine is announced for all the surrounding towns. This has a dramatic effect on the rest of the nation, turning common household pets and pests into vicious attackers.
Anglers from the fishing village of Noyo, California catch what appears to be a monster. The young son of one of the anglers falls into the water and something unseen drags him under the surface. Another angler prepares a flare gun but he slips and accidentally fires it into the deck, which is soaked with gasoline dropped earlier by the boy. The vessel bursts into flames and explodes; everybody aboard is killed. Jim Hill (McClure) and his wife Carol witness the explosion. Later, Jim and Carol's dog goes missing and the pair finds its dismembered corpse on the nearby beach.
In 1901, mail order bride Joanna (Eleanor Parker) arrives from New Orleans at a South American cocoa plantation to meet her new husband, plantation owner Christopher Leiningen (Charlton Heston), whom she has married by proxy.
When the Japanese freighter Eiko-maru is destroyed near Odo Island, the Bingo-maru is sent to investigate, only to meet the same fate with few survivors. A fishing boat from Odo is also destroyed, with one survivor. Fishing catches mysteriously drop to zero, blamed by an elder on the ancient sea creature known as "Godzilla". Reporters arrive on Odo Island to further investigate. A villager tells one of the reporters that "something large is going crazy down there" ruining the fishing. That evening, a ritual dance to appease Godzilla is held during which the reporter learns that the locals used to sacrifice young girls. That night, a large storm strikes the island, destroying the reporters' helicopter, and an unseen force destroys 17 homes, kills nine persons and 20 of the villagers' livestock.
An expedition to an irradiated island brings civilization in contact with a primitive native culture. When one sensationalist entrepreneur tries to exploit the islanders, their ancient deity arises in retaliation.
New Mexico State Police troopers Ben Peterson (James Whitmore) and Ed Blackburn (Chris Drake) discover a little girl in shock, wandering the desert near Alamogordo, New Mexico. They retrace her steps to a mobile home owned by an FBI agent named Ellinson, who was on vacation in the area with his family. The side of the trailer was ripped open from the outside, the rest of the family is missing and no money was taken. A single unidentifiable animal track seems to be the only clue. Then a strange, pulsating high-pitched noise echos out of the desert on the wind. The little girl briefly reacts in fear when she hears the sound, but this is not noticed by those around her.
Two pilots named Shoichi Tsukioka and Koji 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.
The film begins with a farmer named Billy Hoss (Rex Linn) and his wife Ethel waking up in the middle of the night to unusual noises. They and their dog Sparky go outside to investigate, where they find a horse lying dead, violently ripped open. Their dog runs into the dark, and is attacked (and presumably killed off-screen), causing Billy and Ethel to run back in the house where they see a mysterious giant figure behind their home. Once the creature is gone, they come out again and find large footprints on the ground.
Jane Chase une étudiante américaine en zoologie au collège des sciences de Londres est engagée par le professeur Steven Phillip pour s'occuper de sa villa sur la côte.
A nuclear submarine on maneuvers in the Pacific Ocean, captained by Commander Pete Mathews (Kenneth Tobey), comes into contact with a massive sonar contact. The boat is disabled but manages to free itself and return to Pearl Harbor. Animal tissue of great proportions is discovered jammed in its dive planes. A man-and-woman team of marine biologists, Lesley Joyce (Faith Domergue) and John Carter (Donald Curtis), is called in; they identify the tissue as being part of a gigantic octopus. The military authorities scoff, but are finally persuaded after receiving reports of missing swimmers and ships at sea being pulled under by a large animal. Both scientists conclude the sea beast is from the Mindanao Deep, having been forced from its natural habitat by hydrogen bomb testing in the area, which has made the giant creature radioactive, driving off its natural food supply.
The movie begins with a couple on a small sailboat who find a small island and begin to look around. The girl sneakily wanders off while the man ties up the boat. She stumbles across a fence and a small compound, but no one seems to be around. She is then attacked by unknown creatures. The man at the boat is startled by her screams.
In the small mining village of Kitamatsu, on the southern Japanese island of Kyushu, two miners have gone missing. The two men, Goro and Yoshi, had brawled earlier that day, and after they entered the mine to start their shift, the shaft had quickly flooded. Shigeru Kawamura (Kenji Sahara), a tunneling and safety engineer at the mine, heads below to investigate and makes a gruesome discovery: Yoshi's lacerated corpse. Above ground, a doctor examines Yoshi, and discovers the cause of death to be a series of deep gashes caused by an abnormally sharp object. Some of the miners and their families begin to discuss the possibility of the involvement of Goro, who is still unaccounted for, in the death. Shigeru is personally affected by this incident, since his fiancée Kiyo (Yumi Shirakawa) is also Goro's sister.
Strange events are taking place in Okinawa. An Azumi priestess has a terrifying vision of a city being destroyed by a giant monster. A type of metal not found on earth is discovered in a cave by a spelunker, Masahiko Shimizu, who takes it to Professor Miyajima for examination. An excavation led by Masahiko's brother Keisuke accidentally uncovers a chamber filled with ancient artifacts and a mural bearing an ominous prophecy: "When a black mountain appears above the clouds, a huge monster will arise and try to destroy the world; but then, when the red moon sets and the sun rises in the west, two more shall appear to save humanity." Keisuke is joined by archaeologist Saeko Kaneshiro, who translates the prophecy and takes one of the artefacts, bearing the likeness of the legendary monster King Caesar, to study. Two men stalk them, one who speaks to them and claims to be a reporter interested in the story, the other of whom attempts to steal the statue from them but fails and flees.