Horror of the Blood Monsters (also known as "Vampire Men of the Lost Planet" or "Horror Creatures of the Prehistoric Planet") is a sci-fi cult classic and amalgam of footage from three separate movies condensed into a single plot by director Al Adamson. Combining the films "Robot Monster," "One Million B.C." and a Filipino monster movie "Tagani," Adamson deftly weaves the footage into a single narrative with use of special effects, color shifts and a voice-over narration by Theodore Gottlieb to explain away discrepancies. Scientist Dr. Rynning (John Carradine) leads a space expedition to a distant planet of space-vampires to thwart their impending invasion of earth. Upon reaching the vampire planet, the astronaut team encounters far more than ever expected. Caught between warring clans of primitive vampire tribes, horrific monsters and cannibalistic snake-men, the team find unlikely allies against the myriad foes, but whether it will be enough to save them from the vampire scourge remains to be seen.