Charlotte "Charlie" Flanagan wasn't expecting fourth grade to end up like this. In fact, it was her worst nightmare come true. Of all the kids in the world, why did Billy Blake have to come back to her school? Charlie still remembers what happened on the second grade field trip to the zoo, and she has never forgiven Billy. With her life turned upside down, Charlie and her best friend Lucy plan to get Billy kicked out of school. But as their hilarious plot starts to unfold and the unexpected happens, she begins to regret ever thinking that this school isn't big enough for the both of them.