Lemuel P. Twine, the owner of Twine's Tasty Pudding Powder Co. of Witumpka Falls, is pushed into politics by his wife Minerva.  Unknown to Lem and Minerva, however, Lem's backer, local businessman Lester Caldwalader, Sr., is using Lem's entire campaign as reform mayor to ensure the re-election of the current mayor, Moe Carson.

While on her way to a golf date with Caldwalader's son, Lester, Jr., Helen Barbara Twine, Lem's oldest daughter, almost runs over her old boyfriend, Jimmy Hanagan, who has just returned home from college.  Jimmy, having found no work in his chosen field of advertising, has taken a job at Caldwalader's general store.  Later, Helen manages to get Jimmy fired by the jealous Les so the young man goes to work as advertising director for Twine Pudding.  Jimmy comes up with the idea of claiming that Twine Pudding is filled with the nonexistent Vitamin Z, and convinces local scientist, Prof. Asa Quisenberry, to "discover" the miracle vitamin in the pudding.  After his "testing," Quisenberry tells a group of reporters that Vitamin Z, also known as "Zumf," acts as an aphrodisiac on young women.

Soon, sales of the pudding are soaring and Witumpka Falls is making national headlines.  At the same time, Lem's campaign takes off, and Caldwalader becomes even more upset when he learns that the Chamber of Commerce has named Lem as "Witumpka Falls Man of the Year."  Les is also upset, after he reads a newspaper interview with Minerva in which she announces the engagement of Jimmy and Helen.  Desperate to ruin Lem, Caldwalader hypothesizes that Vitamin Z might disappear in Twine's pudding once the powder has aged, and buys some old cases of the pudding to test that theory.

Later, at a luncheon in Lem's honor, Caldwalader announces that chemists have discovered no "Zumf" in the pudding, and Lem is declared a fraud.  Jimmy is then accused of bribing Quisenberry, and in a fit of anger, he walks out on the Twine family.  Nevertheless, Lem continues his mayoral campaign, arguing that the town should be electing a man, not a pudding.

As the campaign comes to a conclusion, Jimmy returns and becomes upset once more when he sees Helen with Les.  That night, while Lem sleeps in his chair, the ghost of his grandfather, Claudius Twine, appears out of his portrait over the fireplace and, along with other deceased relatives, warns Lem of Caldwalader's deceptions.  Lem meets with Jimmy and Quisenberry and tells them of his "dream."  At a restaurant, Jimmy then convinces Moe that Caldwalader has betrayed him, only to have Caldwalader arrive and get into a fistfight with the confused mayor.

The next morning, after Helen and Jimmy spread flyers throughout the town, explaining Caldwalader's trickery, Lem is elected mayor.  Based on Lem's advice, Jimmy goes to the Twine home and gives Helen a spanking.  The couple then makes up, with Claudius looking down, approvingly.