Tang Yan could have been an ordinary top student. But everything changed in 2007. He met three classmates with very different personalities: Ji Yuewei, a noble but innocent beauty; Guan Xinling, who is hot on the outside and cold on the inside; Su Hangfei, who is fresh and refined but has an unfathomable city. But this led to a series of troubles: first, Tang Yan himself was knocked unconscious by an unknown person in the bathroom; then Su Hangfei attacked Ji Yuewei; and then there was a special group called "Two-Sider" mentioned by Ji Yuewei. The biggest doubt is not yet here. A diary written by Tang Yan's class teacher, Lao Liang, revealed an unspeakable secret... A conspiracy that had been buried for more than 20 years seemed to have been revealed just like that.