Casey is one of those horse-happy girls who cannot foresee that she may lose her love for all things equine. She does outgrow her pony, but almost simultaneously, chances to meet Marianna, the owner of Vanity, a tall horse. Luck rules again as the owner falls off the horse and subsequently asks Casey to board Vanity while she's in college. Casey spends the year working Vanity -- trotting around the ring, trying some jumps, etc. Marianna returns in June, having outgrown her boots and jodhpurs, and gives Vanity to Casey. Despite Casey's fanaticism, it's a slow trot all the way -- for young saddle-struck girls only.