It's the invitation of a lifetime. When Judy Barker, the Pine Hollow veterinarian, offers Lisa a chance to visit the stables at the racetrack, Lisa jumps at the opportunity. She's been working on her skills as a photographer, and she'd love to take pictures of some of the Thoroughbreds—especially a beautiful stallion that's training for the upcoming Preakness race.

Then Lisa, Carole, and Stevie uncover what could be a plot to make the stallion so sick he can't run. Will Lisa's photographs help the girls bring a high-stakes schemer to justice?