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.

Jack Burden is a newspaper reporter who first hears of Willie Stark when his editor sends him to Kanoma County to cover the man. What's special about this nobody running for county treasurer? He's supposedly an honest man. Burden discovers this to be true when he sees Stark delivering a speech and having his son pass out handbills, while the local politicians do their best to intimidate him. Willie Stark is honest and brave. He's also a know-nothing hick whose schoolteacher wife has given him what little education he has. Stark loses the race for treasurer, but later makes his way through law school, becoming an idealistic attorney who fights for what is good. Someone in the governor's employ remembers Stark when the governor needs a patsy to run against him and split the vote of his rival. The fat cats underestimate Stark; but Jack Burden, Stark's biggest supporter...