Book 5 Princess Ellie's Moonlight Mystery by Diana Kimpton

Ellie is looking forward to her camping trip with her best frend, 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. Wiil she solve the Moonlight Mystery?