We watch a Standardbred colt born on a California farm that breeds champions. As a yearling, he's hitched to a surrey, and the trainer decides if he'll be a trotter, a pacer, or a show horse. This one, Mortimer, will be a trotter. The film shows us the differences among the three, and the off-screen narrator provides information on the different rules governing each. We then watch training, and the film ends with Mortimer's first race.