Kevin McCarthy and Dana Wynter star in this sci-fi drama directed by Don Siegel. The citizens of a small Californian town begin to complain that their fellow townsfolk are not what they used to be. Local doctor Miles Bennell (McCarthy) discovers the reason behind their sudden personality shifts: extraterrestrials are replacing humans with lookalikes grown in large pods. Bennell struggles to warn the nation of the truth before he too gets the alien make-over treatment.