Prologue: Infected vampire blood was carried to earth millions of years ago by the Tubaton, vampire men from a distant galaxy.Dr Rynning [John Carradine], an aging scientist, is leading a space expedition into Spectrum, an unknown solar system that he discovered. Along the way, the XB-13 runs into a meteor storm and loses contact with ground controllers, Dr Manning [Robert Dix] and his assistant Valerie [Vicki Volante]. Fortunately, neither Dr Rynning or any of the crew, which includes Comnander Steve Bryce [Bruce Powers], Captain Bob Scott [Fred Meyers], Willy [Joey Benson], and Linda [Britt Semand], are hurt, but the XB-13 is forced to make an emergency landing on an unknown planet in order to make repairs. Fortunately, the planet on which they land has an atmosphere exactly like earth, with the exception of some chromatic radiation that makes it change colors.While Dr Rynning waits in the spaceship (he has a heart condition that could cause him to experience a coronary attack in the new atmosphere), the rest of the crew goes exploring. The planet seems to be inhabited solely by prehistoric creatures until they happen upon two groups of cavemen who appear to be fighting each other. Suddenly, a girl wearing a white skin (that looks amazing like a prehistoric bathing suit) runs past them, screaming as she is chased by three of the cavemen. Willy tackles her and, while the girl is knocked out, Linda implants a "communicator" in her brain so that she can understand and speak English. When she comes to, she identifies herself as Malian [Jennifer Bishop] and tells them the story of her people, the peace-loving Tagani, who are hunted by the blood-thirsty Tubatons. At this very moment, the Tagani are engaged in a fierce battle with the Tubaton, from whom Malian was running.Meanwhile, Manning and Valerie are having sex. Attached to their heads are electrodes that lead to a machine with a lot of multicolored tubular lights, a machine that supposedly give the best sex ever. Unfortunately, Manning is too worried about the XB-13 and promises to return a bit later and, this time, turn the machine up to the highest setting.Malian mentions how some of the Taganis are trying to get to the cave where they can get the "firewater" needed to keep their protective fires going. Cmdr Steve thinks that "firewater" might refer to petroleum, which Rynning says can be distilled for rocket coolant, so Malian leads them to the cave where they fill two canisters that Cpt Bob has brought from the spaceship. Steve and Linda then carry the oil back to the ship, while Willy and Bob attempt to return Malian to the Tagani. However, Malian doesn't want to go back to the Tagani without Willy. As Willy and Malian are saying goodbye to each other, Bob is attacked and killed by a Tubaton. Willy and Malian try to make it back to the ship, but Willy suddenly passes out.Rynning orders Steve and Linda to immediately return to the ship. It's a matter of life or death. Steve sends Linda on but goes back to find Bob and Willy. Along the way, he meets with Malian who leads him to dead Bob and passed out Willy. Steve carries Willy back to the ship, where Rynning informs them that their blood tests reveal that the white corpuscles are devouring the red corpuscles due to a deadly virus in the planet's radiation-polluted air. All the people on the planet are doomed. Fortunately, the virus can't survive in the clean air of the earth, but it is necessary to immediately leave the doomed planet."This was a highly civilized and brilliant society at one time. It wasn't enough for them. Not only did they have to acknowledge having such weapons...they had to use them. I have no doubt we'll be equally brilliant one day." --Dr Rynning