A giant octopus, whose feeding habits have been affected by radiation from H-Bomb tests, rises from the Mindanao Deep to terrorize the California Coast.
Dr. Eric Vornoff, with the help of his mute assistant Lobo, captures twelve men for a grisly experiment; His goal to turn them into supermen using atomic energy. Reporter Janet Lawton, fiancée of the local lieutenant, vows to investigate Vornoff's supposedly haunted house.
In a tributary of the Amazon, a monster – half-man, half-fish – is captured and placed in a reservoir in a Florida national park to be observed by scientists.
As a result of nuclear testing, gigantic, ferocious mutant ants appear in the American desert southwest, and a father-daughter team of entomologists join forces with the state police officer who first discovers their existence, an FBI agent and, eventually, the US Army to eradicate the menace, before it spreads across the continent — and the world.
While in London trying to nab several fugitives who stole a million dollars from a U.S. Treasury vault, American federal agent Dennison (Dennis O'Keefe) assists Scotland Yard Insp. McClaren (Philip Friend) in his search for a missing atomic scientist (Paul Hardtmuth). The detective duo discovers that the key to solving both cases may rest with the scientist's daughter (Margaret Sheridan) and her fascinating diamond.
When scientists exploring the Amazon River stumble on a “missing link” connecting humans and fish, they plan to capture it for later study. But the Creature has plans of his own, and has set his sights on the lead scientist's beautiful fiancée, Kay.
The residents of a small town are excited when a flaming meteor lands in the hills, until they discover it is the first of many transport devices from Mars bringing an army of invaders invincible to any man-made weapon, even the atomic bomb.
A Scotsman abruptly breaks off his engagement to pretty Kitty and moves to his uncle's castle in the Scottish highlands. Kitty and her aunt follow Gerald a few weeks later, and discover he has suddenly aged. Some mysterious things happen in a maze made from the hedges adjoining the castle.
A scientist develops a formula which will cause animals to regress to the form of their primitive ancestors, and tries it on himself with disastrous results.
Author and amateur astronomer John Putnam and schoolteacher Ellen Fields witness an enormous meteorite come down near a small town in Arizona. Putnam becomes a local object of scorn when, after examining the object up close, he announces that it is a spacecraft, and that it is inhabited...
Martians come to Earth to build an H-bomb strong enough to blast Earth out of orbit so that Mars can be moved into its place in closer proximity to the sun. Super-scientist Larry Martin, inventor of the first stratospheric-flight spaceship as well as a jet-powered personal flying suit with helmet, is called upon by the government to investigate ramped-up UFO reports occasioned by the Martians' spaceships. The Martians, meanwhile, led by Marex, engage a renegade earth scientist and a gaggle of gangsters to help them steal supplies, operate a menacing robot, and build their bomb. This movie serial in 12 chapters was originally planned as a sequel to "Radar Men From The Moon" with Commando Cody as the hero but at the last moment the main characters' names were changed and all other references to that serial removed from the script.
Research chemist Barnaby Fulton works on a fountain of youth pill for a chemical company. One of the labs chimps gets loose in the laboratory and mixes chemicals, but then pours the mix into the water cooler. When trying one of his own samples, washed down with water from the cooler, Fulton begins to act just like a twenty-year-old and believes his potion is working. Soon his wife and boss are also behaving like children.