The #1 bestselling Magic Tree House series for chapter book readers is ready to whisk you away across the world with Jack and Annie--this time to save sea otters after a shark attack! Perfect for readers ages 6-9! It's bright and early when the magic tree house spins Jack and Annie to Monterey Bay, California. It's their mission to collect sea urchins in the underwater kelp forests! But they know nothing about collecting sea urchins--can a grouchy boat captain help them? Maybe. But Jack and Annie have another problem when Annie finds a badly injured sea otter. They're not supposed to help the otter. but it's the right thing to do. Can they convince the grouchy boat captain to help them? 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 Graphic Novels: Relive the original adventures brought to life with art by Kelly & Nichole Matthews If you're looking for Merlin Mission #40: Eve of the Emperor Penguin , it was renumbered as Merlin Mission #12 when the series was rebranded in 2017.