One day, Class 18, the notorious problematic class in Wutong Middle School received a letter from their future selves. The letter accurately predicted what would happen to their class overthe course of their high school years, and asked them to complete three impossible missions to save Mr. Tangent their sick math teacher. To prevent the misfortunes written in the letter from happening and changing their future, the two groups of bad teenagers that ruled the class called a truce and gradually developed a heartwarming relationship with their teacher on their path towards changing their future.