The Pony Detectives can't wait for the Christmas holidays – they're off to the Abbey Polo Club to see their first polo match, featuring star player Estoni and his horse, Stormchaser. But when the girls start investigating a new case, events take an unexpected turn and Stormchaser's life is left in the balance. The Pony Detectives must act fast if they are to solve the mystery and save the star pony.