During the Tang Dynasty, Crown Prince Li Xinghe traveled incognito and met female coroner Zhang Xiaomeng and Dali Temple Chief Justice Chu Qi. After working together to solve the life and death case, the three of them were accidentally involved in the Red Dress Murder Case. In the process of solving the case, they also involved the long-forgotten fox demon secret room murder case. How will the three solve the strange case in the strange Chang'an?