Two mayors meet and fall in love during a convention in San Francisco.

While attending a convention of the nation's mayors in San Francisco, Mayor Clarissa Standish of Wenonah, Maine, a demure, Harvard-educated, devoted public servant, meets the rough-hewn, outspoken mayor of Puget City, Steve Fisk. A former longshoreman with a lust for life and beautiful women, Steve initially mistakes Clarissa for Sheila, his balloon dancer date for the evening, and inadvertently insults Clarissa. Clarissa forgives Steve's mistake, however, and eventually comes to admire his brazenness. Though concerned that his image might be tarnished if he were seen dating "important" women, Steve soon develops a close friendship with Clarissa. At the same time, Steve's friend, Puget City fire chief Duggan, warns Steve that Henshaw, a crooked Puget City council member, is waging a campaign to discredit him and that he should avoid any bad publicity while in San Francisco. One night, Steve holds an informal committee meeting with other mayors and their wives at the Blue Duck nightclub in Chinatown, but Clarissa objects to the partying and inadvertently insults the wives of the mayors. The festivities come to an abrupt end when Steve sets off a brawl. Clarissa tries to stop the fight by playing the piano and singing the song "San Francisco," but Steve cuts her song short and insists that she flee the club to save her reputation. The escape plan fails, however, and Steve and Clarissa are arrested in a police raid. Police sergeant Hogan, who is determined to keep the matter quiet, releases Clarissa and Steve, but, as Clarissa leaves the station, a photographer takes her picture in front of a "Sobriety Test" room. Though the picture results in a scandal in the conservative town of Wenonah, Clarissa's uncle, Judge Silas Standish, is pleased to see that his niece has finally shed her prudishness. A short time later, Clarissa and Steve are arrested again while standing on a street corner dressed as children for a costume party. Steve is charged with soliciting a minor, but Hogan quickly releases them again. While Steve and Clarissa ride back to the hotel in a taxi, the taxi swerves to avoid hitting some pedestrians, and the two are thrown into each other's arms. A romantic walk down the fog-shrouded streets of Telegraph Hill then sparks a romance between Clarissa and Steve, and they make plans to marry in Puget City. The engagement is called off, however, after Steve accuses Clarissa of being ashamed of his working class background. When Steve learns that Henshaw plans to hold a secret vote to override his veto of a pork barrel construction contract, Steve decides to leave the convention and return to Puget City. Clarissa is heartbroken when she sees Sheila enter Steve's room, as she is unaware that Steve is not interested in Sheila. Steve arrives in Puget City in time to ensure that his veto is not overridden, and then plans to fly to Wenonah to make amends with Clarissa. Confusion abounds when Silas, who has not been told of the cancellation of the wedding, arrives in Puget City to meet his future nephew-in-law. When Steve learns that Clarissa is on her way to Puget City to find her uncle, he quickly arranges a grand welcoming for her at the train station and plans to present her with the key to Puget City. Clarissa is still angry with Steve when she arrives, and will not permit him to explain why Sheila was in his room. Steve eventually gets his chance to set matters straight, however, and the two resume their marriage plans.