Little Joyce Fairfax loves her thoroughbred colt “Satan.” When financial difficulties force her young, widowed mother to sell her estranged grandfather, Judge Boyce, who had disapproved of her mother’s choice of husband, buys him secretly. When the judge also suffers reverses, he enters Satan in the Dixie Stakes where the unscrupulous Silas Morgan tries trickery to prevent the colt from running. He almost succeeds until a mysterious rider comes to the barrier, and rides Satan to victory. When Mrs. Fairfax hastens to the paddock, she finds Joyce very muddy and soiled in her jockey colors, just then Judge Boyce arrives, and the trio are reunited.