Summary: The #1 bestselling Magic Tree House series is ready to whisk you away through time with Jack and Annie! This time, meet famous explorer Leif Erikson and help save a narwhal! When the magic tree house whisks Jack and Annie to Greenland, they're not sure what time they've landed in, but they immediately know what their mission is: save a narwhal! Then they meet a young hunter named Leif Erikson and they ask for his help. But Leif has other ideas... Track the facts with Jack and Annie in the nonfiction companion to this book: Narwhals and Other Whales . Did you know that there's a Magic Tree House book for every kid? Magic Tree House: Perfect for readers who are just beginning chapter books Merlin Missions: More challenging adventures for the experienced reader Fact Trackers: Nonfiction companions to your favorite Magic Tree House adventures If you're looking for Merlin Mission #33: Carnival at Candlelight , it was renumbered as part of the rebrand in 2017 as Merlin Mission #5