A drunken young veteran returns home to find the family horse-breeding business facing ruin.

Pole Shattuck, the wealthy head of an old Kentucky family, goes to court to have Ezra Martingale, the cantankerous head of the family with whom the Shattucks have feuded for years, committed as a public nuisance because Ezra chased him with a shotgun. Steve Tapley, the Shattuck horse trainer, hides Ezra in his cottage on the Shattuck farm to help his friend Nancy Martingale, Ezra's granddaughter. Upon learning that the sheriff has ordered Nancy either to produce Ezra or put up a $2,000 bond, Steve pays the money without telling Nancy. Shattuck then fires Steve. Steve plans to train the Martingale horse Greyboy for free, but Nancy sells the horse to raise the bond money to Slick Doherty from Louisville, without knowing that Doherty is an agent for Shattuck. After Greyboy is slightly injured in a fall, Dr. Lee Andrews, whom Shattuck has hired because of his up-to-date training methods, tells Shattuck says that the injury is liable to be serious because he wants to help Nancy, to whom he is attracted. Shattuck calls the deal off, and Lee then begins to court Nancy, which irks Shattuck's snobbish daughter Arlene. Soon Greyboy is nearly back to normal, but Steve feels that the horse needs a muddy track to win a race. Ezra disappears in search of rain and returns with Pluvious J. Aspinwall, a self-touted rainmaker. At the ball before the race, Steve, seeing Shattuck brag about his horse Emperor, bets him that Greyboy will win and offers as stakes the strip of land over which Martingales and Shattucks have been feuding. Lee convinces Nancy that Greyboy should not race until his injury has healed, but when Steve hears of this, he decides to steal the horse with the help of his black servant, Wash Jackson. The next day, after Ezra has shot some more times at Shattuck, Steve is arrested for hiding Ezra, but Wash gets Greyboy to the track. At the jail, Wash visits Steve, who then applies burnt cork to his face and tries to switch places with Wash and leave. Ordered to dance by the sheriff's deputy, Steve successfully imitates Wash, but the sheriff arrives and recognizes him. Steve nevertheless gets away and heads to the track, where, to convince Nancy to enter Greyboy, Steve's friend, Dolly Breckenridge, falsely states that she overheard Lee bragging to Arlene that he got Greyboy scratched. Hurt by this, Nancy refuses to listen to Lee and tells Steve to do what he wants, but Shattuck has paid the Martingale jockey not to ride. Steve gets Nancy to ride before he is caught by the sheriff. By convincing the sheriff that Greyboy is a sure bet, Steve gets him to go to the betting window, where Steve is able to bet $500. During the race, Pluvious attaches dynamite to a bunch of balloons, and as Greyboy is losing, the balloons hit a water tower and explode, causing the track to become muddy. Greyboy quickly passes the rest of the field and wins, after which Steve confesses his lie about Lee to Nancy. When Ezra chases Shattuck and Doherty with a rifle, Nancy begs Steve to retrieve him, but Steve tells her that's Lee's job now. Pluvious finally gets his rainmaking device to work, and Steve is left in the rain, handcuffed to a fence, while the sheriff goes to collect his money.