The #1 bestselling chapter book series of all time celebrates 25 years with new covers and a new, easy-to-use numbering system! Please come to Camelot. The magic tree house whisks Jack and Annie through space and time to find that the castle of Camelot has been attacked and King Arthur has been gravely wounded. To save the kingdom--and the king--Jack and Annie have only one day to solve a riddle that will help them find a missing dragon! Formerly numbered as Magic Tree House #55, the title of this book is now Magic Tree House Merlin Mission #27: Night of the Ninth Dragon. Did you know that there's a Magic Tree House book for every kid? Magic Tree House: Adventures with Jack and Annie, perfect for readers who are just beginning chapter books Merlin Missions: More challenging adventures for the experienced reader Super Edition: A longer and more dangerous adventure Fact Trackers: Nonfiction companions to your favorite Magic Tree House adventures