The innocent Xiao Yi'an left home for the first time to study at the coveted Sunmo Academy, thinking that he had entered the holy land of study. However, he met the handsome and domineering Gu Xiren. The two people in the same room gradually developed a secret love and made a life-or-death agreement. However, Yan Linchen, a classmate, has always been entangled with Xiao Yi'an. Their secret love can only be hidden in the depths or will it be consummated. Can the obstacles shake their determination? Will they still abide by the green covenant after many years?