The water town teenager Mao No.2 is the long-distance running champion of his school. Every morning, he follows Lianfen, who rides a bicycle to school, and runs to school. On the way to school, there's a mischievous student named Suan tou who teases Lianfen. One day, when Suan tou was teasing her, Mao No.2 happened to be there and gave Suan tou and his group of students a "lesson". Suan tou's mother, Zhou Qin, told Principal Wen about this incident. As a result, Mao No.2 received a school punishment, and his older brother Da Mao also went to apologize to Zhou Qin. Later, Mao No.2's punishment notice disappeared from the school bulletin board, and Principal Wen believed that it was Mao No.2 who tore it down.