In 1895, amateur inventor Joe Belden, a resident of Willow Falls, Indiana, is scorned by almost everyone in town, except his mother, his best friend, Ben Parrot, and his sweetheart, Liz Bullitt. Joe's latest, and most ambitious, invention is a gasoline-burning horseless carriage he is building in his mother's barn. He is overjoyed when his "gasomobile" finally starts up, but his jubilation is short-lived as the barn soon catches fire. After the volunteer fire department, which is headed by Joe, finally puts out the fire, the worried pharmacist, Horace Antler, refuses to sell Joe more gasoline, and Harvey Bullitt, Liz's gruff father, angrily tells him to stay away from her. Liz stands by Joe, but urges him to go into her father's stable business so that they can marry. Visionary Joe can only see how different the future will be with inventions like his gasomobile. The next day, at a town social, Joe is ridiculed by his rival, Yale man Cyrus Random, Jr., but pretty visitor Daisy Lou Shultzer is impressed by Joe, and also Ben, who plays a new kind of music called Jazz. Later, on the way to a hayride, Joe sees a placard for a road race with a $5,000 prize and immediately leaves a furious Liz to work on his gasomobile. Three weeks later, after Joe's invention finally starts to work, he goes to Liz late at night and promises that he will marry her right away if he wins the race, but Bullitt interrupts them and sends Joe off. On the day of the town picnic, Liz is proud when Joe drives his beautiful car into the town square, but the gasomobile soon starts to sputter, prompting chants of "get a horse" from the townspeople. Liz and Joe then argue and she leaves in a huff with Cy. She feels sorry later, though, and is glad when Joe comes to the picnic driving his car. Despite the fact that the gasomobile winds up in the lake due to its lack of a proper steering mechanism, the local girls gush over Joe, causing Liz to become jealous. When Joe later bests Cy in a fistfight over Cy's "taking liberties" with Daisy Lou, Liz misinterprets his chivalry and becomes even more jealous. Some time later, despite the city council's plan to thwart progress by setting the speed limit for horseless carriages at three miles per hour, the town anxiously awaits the big race. Cy, who has bought an "autobug" that runs on ether, also plans to enter. On the day of the Fireman's Ball, as the town celebrates their two autopioneers, Liz bets a dollar on Joe after hearing town barber and bookie Nick Tosca raise the odds to twelve to one on Joe. Liz and Joe then make up, but when Bullitt offers to make Joe his partner and allow him time for inventing anything other than gasomobiles, Joe refuses, resulting in another argument with Liz. Joe then barges past Cy, who pretends that Joe hit him without provocation. Late that night, Bullitt has a change of heart and tells Liz he thinks that stables are no longer profitable and he and Joe should start a new business he has read about, a garage. On the day of the race, all types of horseless carriages arrive in town. Joe needs a push to start, but eventually is in second place behind Cy, who does everything in his power to thwart his rival, including switching road signs. The two men come so close to each other that they each break a wheel and Cy accidentally knocks out Joe, then drives away. A moment later, Liz arrives in her buggy and insists she drive because Joe is dazed, but he soon recovers and takes the wheel. As the finish line approaches, Cy is in first place, with Joe and Liz closing in. As they come closer to the finish, Joe tells Liz to jettison all of the tools and excess weight to help him win, and when she jumps out, the gasomobile wins the race, making everyone in town happy, except Cy.