Dr Miles Bennell returns his small town practice to find several of his patients suffering the paranoid delusion that their friends or relatives are impostors. He is initially skeptical, especially when the alleged dopplegängers are able to answer detailed questions about their victim's lives, but he is eventually persuaded that something odd has happened and determines to find out what is causing this phenomenon. This film can be seen as a paranoid 1950s warning against those Damn Commies or, conversely, as a metaphor for the tyranny of McCarthyism (or the totalitarian system of Your Choice) and has a pro- and epilogue that was forced upon Siegel by the studio to lighten the tone.

Extra-terrestrials flying in high tech flying saucers contact scientist Dr. Russell Marvin as part of a plan to enslave the inhabitants of Planet Earth.

In Downey, the teenagers Chris, Scott and Tim are best friends and decide to drive to a bar downtown to a grungy band's gig. Chris' girlfriend Jackie, meanwhile, goes to a party with her preppy friends. While heading downtown, the trio of friends note that there are no cars on the roads despite the rush hour and then they find that the streets are empty. When they arrive in their destiny, they are chased by zombies and run to the bar. Chris decides to return to Downey while Jackie and her friends are attacked by a bunch of zombies.

A few years from now, Earth will have the first contact with an alien civilisation. These aliens, known as Newcomers...