It's the Christmas holidays and the True Riders are preparing for their final competition of the year, the Mounted Games Cup! They've been training hard, but everything keeps going wrong! First , the friends get caught in unexpected fog which nearly injures Alex and his pony, Rose. Then, there are sightings of a mysterious white mare running around the countryside, sabotaging the competition. Could this be the work of the mean Night Riders or is there a magical snow pony on the loose?