When Blueford H. Smythe, a seemingly prosperous tycoon, returns to his home town of Glenwood, Kansas, he is treated like a dignitary by everyone except the mayor, Jonas Tompkins. Instinctively suspicious of his former classmate, Jonas balks when he hears that Smythe and his secretary, Ambrose Ames, have been discussing with members of the city council a plan to turn Glenwood into a resort. Unknown to the town, Smythe and Ambrose are a seasoned confidence team, who have no trouble convincing the council members to buy stock in their phony company. Determined to protect the school fund from Smythe's scheming, Jonas refuses to cooperate with the council, and consequently he and his family are ostracized by the town. At Ambrose's urging, Smythe calls on Jonas' wife Lyda and, using his status as a former sweetheart, suggests that she pressure Jonas into changing his attitude. To placate the town, Lyda invites Smythe and the resort committee to dinner, but her efforts are sabotaged by her son Freddie, a science whiz, who plants explosives and other gags in the food. After Jonas announces that, as mayor, he is prohibiting the sale of stocks, the town rallies to have him impeached. Just before the special election, however, Bill, a young reporter who is engaged to Jonas' daughter Alice, undertakes an investigation into Smythe's past. On the eve of the election, Bill receives a wire from the F.B.I. suggesting that he photograph Smythe for positive identification. Bill tricks Smythe into posing for him, then leaves with the photograph for the regional F.B.I. office. To prevent the town from impeaching him before Bill returns, Jonas and Freddie engineer a series of election stalls. With only seconds to spare, Jonas is saved by the arrival of an F.B.I. agent, who announces to the stunned town that Smythe and Ambrose are notorious confidence men. At last vindicated, Jonas is re-elected by a landslide.