While on vacation, rancher Hopalong Cassidy and his partners, Lucky Jenkins and California Carlson, pass through Mesa City in time for the town festival. Determined to win the square dance contest, California buys a new suit and a suitcase to put it in. When the bank is robbed of the town's savings, which have been earmarked for an irrigation project, one of the culprits, Ace, knocks out California while escaping and mistakenly switches suitcases with him. Later, California discovers the money, and is seen hiding it in his hotel's dumbwaiter by the hotel clerk, Jed. Jed accuses California of the robbery, but when California returns to his room to show Hoppy the money, it is gone. After California is arrested, Hoppy and Lucky start an investigation. The robbery was ordered by Dunning, who is heading the irrigation project. When Jed tries to flee town with the suitcase of money, Hoppy holds him up, but is shot in the arm by Dunning, who kills Jed. Dunning and his gang flee town in a gasoline-powered buggy, and are pursued by a posse. After the gang seeks refuge in a shack, a gunfight ensues, which ends with the gang's arrest. When the suitcase is found empty, Hoppy assures Dunning and the sheriff that the money is at the hotel, which is owned by town mayor Patton. When Patton insists that he is innocent, Hoppy admits that he found the money after California was arrested and mailed it to Patton for safe-keeping until Dunning was exposed. Now Hoppy, Lucky and California leave town, and Hoppy bets his partners that his horse, Topper, can beat them in a one-hundred-yard race.