Aliens are everywhere, and they're attacking planet Earth in one of Ray Harryhausen's most amazing stop-motion sci-fi classics. Dr. Russell Marvin (Hugh Marlowe) works for Operation Skyhook, a government task force sending rockets into space to probe for future space flights. But when the rockets begin mysteriously disappearing, Dr. Marvin investigates along with his wife and assistant, Carol (Joan Taylor), only to find the rockets are being intercepted by an army of space aliens who give humanity an ultimatum: loyalty or death! As the aliens begin attacking cities and landmarks across the Earth including an unforgettable assault on Washington, D.C. it's up to Dr. Marvin and his wife to figure out how to stop these diabolical creatures before it's too late.