Based on

Movies like Racing Romance (1937)

Garage owner Harry Stone buys a racehorse, Brownie, from Peggy Lanstone and, according to formula, hires Peggy as the steed's trainer. When the filly finishes a mere second in the Oaks, Harry's snooty fiancee, Muriel, who never liked the setup anyway, disgustedly heads for greener pastures. Harry promptly marries Peggy, and, after an official investigation of the Oaks' results, Brownie gets revenge on the fickle Muriel.