In the early years of Tang Zhenguan, Chang 'an cases occurred frequently. First, there were many murders outside Kaiyuan Gate, and then the reappearance of the ancient Han Dynasty Ranger Assassin Organization. A series of events around the palace dignitaries and the secret history of the royal family have occurred frequently, such as cursing the imperial power with Woodenhead, and frequent Zhong Nanshan strange phenomena. As a captain, Wei Chifang was unable to solve the case, and Princess Fuyun, the daughter of Princess Pingyang, who was commanded by a "female soldier", was repeatedly implicated. With the help of Li, a talented teenager who lives in seclusion in Chang 'an, she solved the case with China's classical medicine and science and prevented the tragedy from happening. In the process, Li also fell in love with each other. However, in order to complete the mission with the pro-Shatuo people, Fuyun is far away from home.