Dr. Russell Marvin heads up Operation Skyhook, which is tasked with sending rockets into the upper atmosphere to probe for future space flights. Unfortunately, all the rockets are somehow disappearing. While investigating this strange occurrence, Russell and his new assistant/wife Carol Marvin are abducted by a flying saucer, where the aliens demand to meet with certain people in order to negotiate. But it was a trick; the aliens only wanted to kill them. The invasion has begun and if Russell and Carol can't find a way to get past their defenses and stop these creatures, it may be the end of the human race.