In classic E. Nesbit tradition, Jack's wishes go awry while he and his sister Annie, seven, are time traveling. Reluctantly followed by her eight-year-old brother, Annie enters a mysterious treehouse full of books. Examining a dinosaur book, Jack blurts, "I wish I could see a pteranodon for real''—whereupon one flies in, with a rushing wind. Like Dorothy and Toto, they're blown to a land of adventure: the treehouse takes them to the Cretaceous Period, where they meet a triceratops and a duck-billed dinosaur and find a gold medallion engraved "M.'' Elation gives way to terror when a tyrannosaur shows up; Annie escapes, but Jack is cut off while retrieving his pack and the book. Just in time, the pteranodon flies him back to the treehouse, and a hasty wish spins them safely home, to ponder several questions: Whose treehouse? Why all the books? Who is "M''? In the "First Stepping Stone'' series, this initial "Magic Tree House'' book is a fast-paced tale offering both mystery and dinosaurs—powerful enticements for newly independent readers. Illustrations not seen. (Fiction/Young reader. 6-9)