If there's a problem in school, there's no substitute for the world-saving substitute teachers of the S.O.S.! This is the fifth book of this hilarious, highly illustrated early chapter book series. Keep your friends close and your enemies closer! When Snowball, the puffball hamster in Ms. Kim's classroom, accidentally sips the teacher's leftover protein shake, she transforms into a monster like Beacher Elementary School has never known before. It's all hands on deck to stop Snowball before it's too late. And to do that, Milton Worthy is going to do have to team up with Noah, the part-time classroom ferret, full-time evil mastermind! Will Milton and Noah be able to work together in time to stop Snowball and save the world? HarperChapters build confident readers one chapter at a time! With short, fast-paced books, art on every page, and milestone markers at the end of every chapter, they're the perfect next step for fans of I Can Read!.