In Old Kentucky Nov 28, 1935

Horse trainer Steve Tapley is caught between the feuding Martingale and Shattuck families. He sides with young Nancy Martingale and her grandfather Ezra, and the feud is to be resolved by a horse race between the favorites of each family. Unfortunately, the Martingale's horse, Greyboy, only runs well in mud. And it hasn't rained in a long time.