Princess Ellie is pony-mad! She loves her adorable ponies, and hates all the boring royal rules princesses have to put up with. Ellie is looking forward to her camping trip with her best friend, Kate, and her two ponies, Moonbeam and Rainbow. There'll be no servants, no governess and - best of all - no rules! But when she hears strange noises in the night, Ellie decides that camping isn't as much fun as she thought. Will she solve the moonlight mystery?