Considering what a shoestring budget Herman Cohen's first production was made on, it's almost a masterpiece.
Sci-fi mainstay Richard Denning awakens one morning in the city, to find there's no city. Everyone in it is gone - almost. He runs into frightened Kathleen Crowley, and eventually into another couple, Virginia Grey and Richard Reeves, who aren't sure whether the world's ended or not (and aren't frankly too worried about it, if it has), and so celebrate with champagne just in case. In time, an on-the-lam hood joins the group, making them all wonder what is worse: invaders from beyond, or their own next door neighbors.
And what's come from beyond are alien robots - clunky tin-can jobs, with a single cyclopean eye that fires a killer heat-ray - intent, for whatever reason, on eliminating the local populace. The military has the city cordoned off, and is busy studying the single robot they've captured. They theorize it was sent by a humanoid race, probably from Venus, as a vanguard for invasion.
Can they find the robots' weakness, and exploit it in time? Will the abandoned city's survivors manage to find a way to survive each other, let alone the invading metal men?
This movie succeeds despite its remarkable cheapness - only one robot was made, recycled to represent an army of them - but its script is fairly trite. It's still worth watching, though, for the performances and the end-of-the-world fun with killer robots.