Space scientist Dr. Russell Marvin (Hugh Marlowe) and his wife Carol (Joan Taylor) are working on a secret missile project, but every time their rockets are launched, they are intercepted and destroyed by the more advanced technology of mysterious flying saucers hovering near the Earth. The alien race has completely surrounded the planet, giving the Earth sixty days to surrender. The enemy spacecraft appear indestructible, and Marvin sets out to find a weapon that can defeat them. The special effects of stop-motion animator Ray Harryhausen are legendary, most notably in the scene in which flying saucers attack the Capitol building in Washington, D.C.
