Yoto says: Susan Simmons has discovered that her new teacher is secretly an alien. Now she has to find a way to save the school!

Susan Simmons can tell that her new substitute teacher is really weird. But she doesn’t know how weird until she catches him peeling off his face — and she realizes that “Mr. Smith” is really an alien! At first no one will believe her, except Peter Thompson, the class brain. When Peter and Susan discover Mr. Smith’s horrible plans for their classmates, they know they have to act fast to get rid of their extraterrestrial visitor… and save the rest of the sixth grade class from a fate worse than math tests!