Magic Tree House Series57 primary works • 109 total worksFantasy for children ages 5-8. In 2017 the Merlin Missions were republished as an independent series with new numbering. What was book #29 "Christmas in Camelot" is now #1 of the Merlin Missions and so forth. In 2017 a new book 29 "Big Day for Baseball" was published under the Magic Tree House series. To avoid confusion all Merlin Mission books have been moved to a new list. see Merlin Missions" If you're looking for Merlin Mission #30: Haunted Castle on Hallow's Eve, it was renumbered as part of the rebrand in 2017 as Merlin Mission #2.If you're looking for Merlin Mission #31: Summer of the Sea Serpent, it was renumbered as part of the rebrand in 2017 as Merlin Mission #3.If you're looking for Merlin Mission #32: Winter of the Ice Wizard, it was renumbered as part of the rebrand in 2017 as Merlin Mission #4. Book 55 was the last to be published as part of magic tree house before making them an independent series. Depending on the publication date on the book you may find the old magic tree house number (especially in libraries) or the new Merlin Mission number.