An American rocketship returns from a flight to Venus but crashes, leaving behind a cute little creature back from Venus, unfortunately, the little creature doesn't stay little for long and threatens to tear apart the Colosseum.

Dr. Russell Marvin heads up Operation Skyhook, which is tasked with sending experimental rockets into the upper atmosphere. Unfortunately, all the rockets are somehow disappearing. During the final rocket launching, a flying saucer lands and the military fires upon the aliens, triggering the destruction of the installation and a cryptic warning from the aliens. In response, Dr. Marvin and his colleagues develop an anti-magnetic beam weapon to disable...