Terry is a teenage girl whose Uncle Willy, a horse trainer, dreams of winning the Derby. He bets everything on his horse Sunset, then collapses and dies after it loses.
Now living with wealthy Aunt Martha, the girl is convinced that Uncle Willy has been reincarnated as a horse named October. A psychology professor, Bentley Bassett, writes a book about Terry, which is used in a sanity hearing against her by crooked relatives who want dying Aunt Martha's money.
Bassett uses college funds to help Terry buy the horse. They enter October in the Derby, where other bettors join them in cheering "Uncle Willy" to victory.
