During the heyday of the Tang Dynasty, Di Renjie, who was only 20 years old, went to Beijing to take the Mingjing exam, and Wu Zetian personally supervised the exam. An assassin disguised as a candidate suddenly appeared, and the exam room was in chaos. Di Renjie chased the mysterious assassin and accidentally discovered that the assassin was a woman disguised as a man, and the assassin escaped in the chaos. Wu Zetian ordered Di Renjie to continue to track down the assassin's origins. Di Renjie found that the other party's assassination was carefully planned in detail. The young Di Renjie was determined not to give up until he got to the bottom of it. Di Renjie was outstanding in talent and had made great contributions to protecting his master, so he soon became a judge in Bianzhou. In Bianzhou, Di Renjie met his first love, Chu Yun. Chu Yun was five years older than Di Renjie, and Chu Yun took care of Di Renjie like a sister. Later, Chu Yun married Wang Yan, the second son of Wang Benli, the left secretary, and Wang Yan died unexpectedly on the wedding night. When they meet Di Renjie again at this time, they are both moved. However, Chu Yun, who has experienced a great change, has rationally realized that she and Di Renjie have no future. However, Di Renjie finds that Wang Yan's death was not an accident. Tragedy occurs one after another, and several people in the Wang family die one after another. The crime scene is strangely beautiful, and the undercurrent of emotions between Di Renjie and Chu Yun adds mystery to the case.