Reverend John Burnside, American missionary in the Far East, prepares to return home after twenty years to take up the fight against Communism. The Reds imprison him and send in his place a spy who is his double, but who is instructed to come out for Communism. The spy is accepted in Burnside's home town, and he reports to local Communist headquarters, where James John, prominent local businessman but in reality a Red agent, has instructions to assist him in all details of his mission. He does a series of personal appearances and radio interviews and talk shows, using an anti-Communist approach. Meanwhile, he is getting the chance to see how Americans live, and the part that religion plays in their lives, and there is also a slight romance between him and Burnside's former sweetheart, Louise Cannon, who thinks he is the man she knew twenty-years previously. Then comes the night when he is scheduled to go on the air on an international hook-up, at which time he is do an about-face and speak on the virtues of Communism. Instead, he tears up his pro-Communist speech and denounces Communism. Red agents kill him and they are rounded up by the FBI. The real Burnside, in a North Korean prison, hears the broadcast.