A bizarre murder has occurred in St. Martin's High School resulting in the death of a military official's son. Rookie policeman Chen Hu goes undercover at the school to investigate the case. In order to crack a case, undercover cop Chen Hu has no choice but to miserably return to high school life. He is bad at studying and becomes a laughing stock in front of the other students. At the same time, he is navigating various factions to investigate the mystery behind the death of He Man Jun. What is the truth and who is the real culprit?