The title tells all in this ultra low budget sci-fi film which boasts flying saucers created by visual effects legend Ray Harryhausen. It aims for a documentary style realism, with voice over narration and lots of pseudo-science, adapted from a non fiction book by Major Donald Keyhoe, formerly of the US marines who headed up a national committee on UFOs!
But of course it's just an entertaining B film. It may be poorly budgeted, but it had some advantages in being made for Columbia pictures who had Harryhausen under contract. He creates a good space ship though his models of the collapsing landmarks of Washington DC are no better than ok.
The story mimics the cold war in that it depicts a rapid escalation of military capability, though there is no nuclear. The humanoid invaders (their planetary home is left vague) have an effective ultra-sonic weapon and the Americans invent an electro-magnetic ray gun which interferes with their engines. Although at times a six shooter has to do.
Hugh Marlowe is pedestrian and careworn enough to play a research scientist, but perhaps not sufficiently charismatic for the action hero he becomes. But he does have an exceptionally sexy assistant/wife in Joan Taylor. This is a pioneering film. Anyone today showing a sky full of UFOs over the monuments of a world famous city is doing nothing that Fred Sears and Harryhausen didn't do first. It's a must-see for fans of fifties sci-fi.