Morgan le Fay, the magical librarian of Camelot, challenges Jack and Annie to find the answers to four riddles. To do so, they must travel under the sea and to the Wild West, the African plains, and the frozen Arctic. It’s a difficult and dangerous task, but if Jack and Annie succeed, they will become Master Librarians! Books in this set include: (#9), (#10), (#11), and (#12). The Magic Tree House series has been a beloved favorite for over 25 years and is sure to inspire a love of reading—and adventure—in every child who joins Jack and Annie! • Magic Tree House: Adventures with Jack and Annie, perfect for readers who are just beginning chapter books • Magic Tree House Graphic Novels:  Jack and Annie's original adventures come to life with full-color, vibrant art, perfect for graphic novel fans and reluctant readers • 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