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.
Warned that it is haunted, a skeptical young couple buy a rundown yacht and fix it up to be their home-on-the-sea, only to slowly realize that it really is haunted.
The Singer Duke Mitchell meets Sammy Petrillo in this parody of Martin & Lewis. They arrive on a jungle island, where a mad scientist played by Bela Lugosi makes human experiments.
The owner of a plantation in the jungle marries a beautiful woman. Shortly afterward, he is plagued by a strange voodoo curse which transforms him into a gorilla. But is his transformation real or is it all in his head?
Iemon Tamiya is an impoverished masterless samurai who craves a better life, which he cannot have because of his marriage to Oiwa, who is completely devoted to her husband.
On the beach one night, Christine Faber, two years a widow, thinks she hears her late husband Paul calling out of the surf...then meets a tall dark man, Alexis, who seems to know all about such things. After more ghostly manifestations, Christine and younger sister Janet become enmeshed in the eerie artifices of Alexis; but he in turn finds himself manipulated into deeper deviltry than he had in mind...
A woman is married to the son of a doctor, the proprietor of a private sanatorium, where she is under unwilling treatment. Both the son and the doctor indicate they want the marriage dissolved. Arriving at the scene is a mysterious personage identified as the doctor's brother who formerly was a stage magician in Europe. He is accompanied by a threatening dwarf...
A schooner disappears at sea without a trace. Years later, evidence of possible survivors prompts the mother of the schooner's mate Jose to hire a tuna boat to investigate. They discover the lad living happily on a South Seas island, and, when he refuses to leave with them, they abduct him. However, Jose gets revenge by leading the ship into the lair of a mysterious giant manta ray.
A demented archaeologist discovers a living, breathing serpent creature known to the Aztecs as Quetzalcoatl and accidentally kills his wife by giving her one of the beast's feathers, causing the creature to track her down and slaughter her. Using this knowledge he exacts revenge upon his enemies by placing one of the feathers on his intended victim and letting the beast loose to wreak havoc.
Architect Walter Craig, seeking the possibility of some work at a country farmhouse, soon finds himself once again stuck in his recurring nightmare. Dreading the end of the dream that he knows is coming, he must first listen to all the assembled guests' own bizarre tales.
Leo, a former convict, is living in seclusion on an island with his step-daughter, the daughter of his late wife. Leo was framed by a group of former business associates, and he also suspects that one of them killed his wife. He has invited the group to his island, tempting them by hinting about a hidden fortune, and he has installed a number of traps and secret passages in his home. He is aided in his efforts by a former cell-mate who holds a grudge against the same persons. When everyone arrives, the atmosphere of mutual suspicion and the thick fog that covers the island promise a tense and hazardous weekend for everyone.