 Chemist David Palmer comes back to his hometown in Indiana to get married to his girlfriend Ruth, a schoolteacher. He finds his father excited about the harness racing potential of a new mare that he s just traded for. When the mare is injured while winning her first race, David s father uses her for breeding, and she has a colt named Dan Patch, who proves exceptionally fast. Meanwhile, Ruth becomes increasingly frustrated with David s continued interest in horses, and with his friendship with his father s trainer and the trainer s daughter.