The #1 bestselling chapter book series of all time celebrates 25 years with new covers and a new, easy-to-use numbering system Getting the facts behind the fiction has never looked better. Track the facts with Jack and Annie

When Jack and Annie got back from their adventure in Magic Tree House Merlin Mission #11: Dark Day in the Deep Sea, they had lots of questions. How big is a giant squid? What is a dragonfish? How do deep-sea creatures find food when it's so dark down there? What do scientists think mythical sea monsters might really be? Find out the answers to these...