After their car breaks down in an eerie small town, a young couple are forced to spend the night in a remote cabin. Panic ensues as they are terrorized by three masked strangers who strike with no mercy and seemingly no motives.

In New York, Felix, a neurotic news writer who just broke up with his wife, is urged by his chaotic friend Oscar, a sports journalist, to move in with him, but their lifestyles are as different as night and day are, so Felix's ideas about housekeeping soon begin to irritate Oscar.

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.