If you watch 1950s sci-fi much, then you’re familiar with John Agar. Using a flashlight, he conquered an entire civilization in “The Mole People”; he saved a small Arizona town from destruction in “Tarantula”; but here, he really excels—Agar saves the entire universe! When scientist Steve (Agar) and his assistant Dan (Robert Fuller) notice a “blast of radiation” from Mystery Mountain, they decide to investigate. In a nearby cave, they’re attacked by a giant floating brain with eyes, which kills Dan with a bright light and then (in a very inept special effect) hides in Agar’s body.
Back at the lab, the brain emerges from Steve, introduces himself as “Gor” from the Planet Arous, and tells Steve he’d better cooperate—or else. Since Gor is so powerful, he can control everything Steve does, and pretty soon Steve starts getting quite lecherous with his fiancée Sally (Joyce Meadows). This has to be some sort of cinema first…a sex-starved floating brain! Later, Sally and her dad John (Thomas Browne Henry) are visited by yet another floating brain, this one’s named “Vol” and is a law-enforcement brain from Arous. Vol announces that he also needs a body to hide out in, and after thinking it over, decides to hide in Agar’s dog, George. Not silly enough yet? Just wait….
When he’s not pawing Sally or tormenting Steve, Gor blows up a passenger plane, kills the local sheriff, burns up an Army colonel, and sets off a nuclear explosion. He then assembles representatives from all the world’s countries and tells them that they must help him construct a fleet of spaceships so he can conquer Arous, then the universe! (At least Gor doesn’t think small.)
Things are looking pretty bleak, so Sally has a chat with Vol. He tells her that Gor could conceivably be killed by a direct blow to the top of his, uh, cerebrum in the area of the “Fissure of Rolando”. She leaves a note to Steve telling him about Gor’s weakness, so when Gor emerges again, Steve grabs a convenient ax, and beats the offending brain to death in a bravura climax.
Probably the most fascinating thing about this movie is that the cast keeps perfectly straight faces throughout the whole film. If you’re in for vintage entertainment with the most outrageously silly sci-fi plot of all time, you should watch this.