When the first manned flight to Venus returns to Earth, the rocket crash-lands in the Mediterranean near a small Italian fishing village. The locals manage to save one of the astronauts Colonel Calder, the mission commander. A young boy also recovers what turns out to be a specimen of an alien creature. Growing at a fantastic rate, it manages to escape and eventually threatens the city of Rome.
In California, an old man grieves the loss of his wife, and dies the day after she is buried. However, the space soldier Eros and his mate Tanna use an electric device to resurrect them both, alongside the strong Inspector Clay, who was murdered by the alien-controlled dead couple. When the populations of Hollywood and Washington DC see flying saucers on the sky, a colonel, a police lieutenant, a commercial pilot, his wife and a policeman try to stop the aliens.
A group of scientists travel to a remote island to study the effects of nuclear weapons tests, only to get stranded when their airplane mysteriously explodes. The team soon discovers that the tests have given rise to crabs mutated into intelligent, impervious, telepathic giants intent on increasing their numbers by breeding, then travelling to populated areas to feed, and which do not intend to be stopped by their discoverers.
Five individuals from five nations, including the USA, USSR, and China, suddenly find themselves on an alien saucer, where an alien gives each a container holding three capsules. The alien explains that no power on earth can open a given container except a mental command from the person to whom it is given, then anyone may take a capsule and, by speaking a latitude and longitude at it, cause instant death to all within a given radius: thus each of the five has been provided with the power of life and death. Then, they are given 27 days to decide whether to use the capsules, and returned to the places from which each one came...
A scientific experiment involving subjecting a corpse to an extreme charge of electricity accidentally revives an executed criminal and makes him impervious to harm, allowing him to seek revenge on his former partners, and deal similarly with anyone else who gets in his way.
A marine biologist and a government agent investigate mysterious deaths and rumors of a sea monster in a secluded ocean cove, and find themselves involved with a marine biology professor conducting secretive experiments, international spies trying to steal his secrets, a radioactive light on the sea bottom, and the malevolent thing which guards it.
After a nuclear attack, an unlikely group of survivors, including a geologist, a crook and his moll, and a prospector, find temporary shelter in the remote-valley home of a survivalist and his beautiful daughter, but soon have to deal with the spread of radioactivity - and its effects on animal life, including humans.
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.
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.
A mad scientist, Dr. Aranya (Jackie Coogan), has created giant spiders in his Mexican lab in Zarpa Mesa to create a race of superwomen by injecting spiders with human pituitary growth hormones. Women develop miraculous regenerative powers, but men mutate into disfigured dwarves. Spiders grow to human size and intelligence.
Commando Cody, 'Sky Marshal of the Universe', works with American scientists Joan Gilbert and Ted Richards in the development of a flying suit and a rocket to the Moon. When the nation's defences are being sabotaged and destroyed, Cody learns that an atomic-gun is being used and that the men on the moon are the culprits.
It is 1865 and Union prisoners use a military balloon to escape a Southern prison camp near the end of the Civil War. The balloon drifts for days and finally lands on a mysterious volcanic island with very unusual inhabitants. Also landing, in a better aircraft, is Rulu, a visitor from Mercury. She seeks a radio-active material that will enable her to manufacture an explosive that will destroy the world or, at least, the portion known as Earth in this 15 Chapter Serial from the 1950s.
Prof. Millard pretends to be dead and helps Jeff King ferret out Vulcan, the evil traitor at the science academy. Donning his Rocket Man costume King goes from one hair raising rescue to the next in order to keep the newly invented Decimator out of the clutches of Vulcan and his minions.
Claire Forrest seeks her kidnapped scientist father, hidden somewhere on Mystery Island. He is held and forced to work on diabolical inventions by Captain Mephisto, a costumed villain.
Dr. Paul Carruthers is frustrated because he thinks his employers, Mary Heath and Henry Morton, have cheated him out of the company's profits. He decides to get revenge by altering bats to grow twice their normal size and training them to attack when they smell a perfume of his own making. He mixes the perfume into a lotion, which he offers as a gift to Mary and Henry. When they turn up dead, a newspaper reporter decides to investigate.