From Mo Willems, creator of the revolutionary, award-winning, best-selling Elephant & Piggie books, comes this breakout beginning-reader series. An ensemble cast of Squirrels, Acorns, and pop-in guests host a page-turning extravaganza. Each book features a funny, furry adventure AND bonus jokes, quirky quizzes, nutty facts, and so, so many Squirrels.In Who is the Mystery Reader?, Zoom Squirrel tries out a new superpower with help from a mysterious Mystery Reader. But will the Squirrel pals ever find out who the real Mystery Reader is? Do you know more about reading than the Squirrels do? You will by the end of this book!