Swedish-American Katrin Holstrom bids farewell to her Midwestern farm family and heads for Capital City, where she plans to pursue a career in nursing. While waiting for the bus, she is picked up by barn painter Adolph, who tries to force her to spend the night in an auto court by pretending his jeep is broken. When Katie shows Adolph just how well the jeep is running, he becomes flustered and backs into a car. The trusting Katie advances Adolph the necessary repair money and is dumbstruck when she discovers the next morning that he has left her nearly penniless at the auto court. Katie eventually makes her way to Capital City, but instead of reporting to nursing school, she takes a temporary job as a maid to rebuild her savings. Although her employers--Glenn Morley, a young Congressman and son of a former U.S. Senator, and his kind but worldly mother Agatha--are impressed by her openness, Katie's supervisor, the crusty Joseph Clancy, warns her not to talk politics while serving. During a political party celebrating the victory of Glenn's fellow Congressman, Wilbur Johnson, however, Katie ignores Clancy's advice and reveals her hostile feelings about Johnson. Later, Glenn, who is attracted to Katie, asks her why she dislikes Johnson, and she tells him that she believes in the right to a minimum wage, legislation that Johnson opposes. Although Glenn is romantically connected to Virginia Thatcher, a political reporter, he and Katie grow close over the next few weeks. Later, when Katie announces that she is leaving for nursing school, Glenn, who is headed for Europe, implores her to stay. She agrees to remain until he returns from Europe, and he suggests that during his absence, she take some night classes. Soon Katie is studying economics and politics and is helped by Clancy and Agatha. Glenn's homecoming coincides with Johnson's sudden death, and Katie finds herself at odds with Glenn's party's choice for his replacement--Anders J. Finley. During a rally for Finley, Katie stands up and begins questioning his dubious voting record. Her protests stir up the partisan crowd, and reports about her behavior attract the attention of the opposition party. To Katie's surprise, the opposition party leader invites her to run against Finley, and even though Agatha swears to fight her, Katie accepts. Although saddened by Katie's disaffection, Glenn helps her to improve her oratorical skills and wishes her well in the race. As the election nears, Finley's lead over Katie grows narrower and narrower. Then, just two days before the election, Adolph approaches Agatha and Finley and infers that, during their trip to Capital City, he and Katie slept together. Although Agatha at first orders Finley not to repeat Adolph's story, she finally agrees with her cronies that using Adolph's lie is the only way to win. Glenn, however, announces he will quit the party if Adolph's story is printed, and when it does appear the next day, he drives to the Holstrom farm, where Katie has gone. Katie accepts Glenn's proposal, but is admonished by her father not to quit the race, but to fight for the truth. Moved by Mr. Holstrom's words, Katie and Glenn return to Capital City and are joined by a repentant Agatha, who gets Finley drunk enough to admit that he is a white supremacist. Finley also tells Agatha that he paid Adolph to lie about Katie and reveals where his fascist cohorts are hiding him. Katie and Glenn track Adolph to a remote lake and, after a fierce fight with Finley's men, are able to force Adolph to issue a public retraction. Katie then wins the election by a landslide and is carried by Glenn over the threshold at the House of Representatives.