In their third chapter book adventure, the princesses are loving life in the ever-changing, magical castle—especially after the Mysterious Messenger shows up with a map of the castle, and they realize that there is a new room they've never seen. They are determined to find it! But when they do, they realize there is no way to get into the room. The clever princesses must use their detective skills to figure it out. When they finally get into the room, they are delighted by what they find—an epic indoor clubhouse!