After a catastrophic atomic blast sends Moonbase Alpha drifting through space, its 300 inhabitants face uncertainty. When a rescue team arrives aboard a faster-than-light ship, excitement fills the base. However, Commander John Koenig, recovering from a concussion, perceives terrifying aliens instead of friendly rescuers. These extraterrestrial beings, desperate for radiation, manipulate the crew into believing they are celebrating a return to Earth while plotting to unleash nuclear waste that could obliterate the Moon. Koenig races against time to unveil this sinister plot and protect his crew from imminent destruction.