Spike, Tristan, Hattie and Monica are working pupils who look after the horses at Mrs Cooper's Sheoaks Equestrian School. It's been a terrible year, with the drought driving up the cost of feed and making Mrs Cooper wonder whether she can keep the school going. Spike knows that her horse, Duke, is the best riding school horse ever, but he's about to be retired. Mrs Cooper has bought another horse to take Duke's place but how could any horse be...