An expedition to the Moon encounters a race of "Cat-Women", the last eight survivors of a 2-million-year-old civilization, deep within a cave where they have managed to maintain the remnants of a breathable atmosphere that once covered the Moon. The remaining air will soon be gone, and they must leave if they are to survive. They plan to steal the expedition's spaceship and migrate to Earth.
Through the use of their telepathic ability, the Cat-Women have been subliminally controlling Helen Salinger (Marie Windsor) so she can win the navigator slot on the expedition and lead the crew to their location. Once Helen and the male members of the crew arrive on the Moon, the Cat-Women take complete control of her mind. They are unable to control the men's minds, but they work around this obstacle, with Helen's help, and the use of their superior abilities and feminine wiles. "Show us their weak points", one says to Helen. "We'll take care of the rest".
Along with telepathy, the Cat-Women have the ability to transport themselves unseen from place to place in their living space. They use this ability to steal the crew's spacesuits from the mouth of their cave, where they were left unguarded.
Using Helen to smooth things over after an earlier failed attack on the crew, the Cat-Women approach the men openly. Food and drink are brought out and a party ensues. Kip (Victor Jory) is suspicious after discovering the spacesuits are missing; he confronts the Cat-Women's leader Alpha (Carol Brewster), who promises to return them in the morning. Kip sits alone, unable to intervene, while the Cat-Women exploit the "weak points" of expedition commander Laird (Sonny Tufts) and the other men.
Soon the Cat-Women have learned how to operate the spaceship and are well on their way to success. But Lambda (Susan Morrow) falls in love with crew member Doug (William Phipps) and tells him of the plot. Carrying three spacesuits, Alpha, Beta, and Helen make a break for the spaceship. Lambda teleports ahead to delay them and is killed by Beta (Suzanne Alexander). Kip catches up and fires several shots, killing Alpha and Beta, while leaving Helen uninjured. In short order the expedition manages to escape and begin their return trip to Earth.
Who plays Lamba?
Susan Morrow