In the Lantern Festival, the people pray for the blessing of the Empress Wu Zetian, but a strange beast with a full body of fire appears. It is said that eating the flesh and blood of the unicorn can cure all diseases, so Wu Zetian orders the Secretary of the Da Lisi, Xue Xin, to find out the truth within seven days. When the young Dee comes to Chang'an to be promoted to the position of "Chancellor" of the Da Lisi, he learns of a strange case at the Shang Yuan Festival and that he needs to wait until the case is solved before he can report to the court. Dee, who had wanted to wait for his job to be solved, is intrigued by this strange case and becomes involved in it by mistake.
