Pan Tianzhu, a famous detective in Beijing, is short and capable, and is known as the "Five-foot Detective". However, as he approaches retirement, he has not solved any cases for nearly ten years, and farces are frequent. The chief detective is unwilling to keep him in Liushenmen to cause trouble, and demotes him to Wuzhen as a detective. Pan Tianzhu, who has just arrived, realizes that this seemingly peaceful town is actually very strange. The tragic deaths of Li Youqian, Widow Wang, and Lawyer Wang have confirmed his speculation. Wu Suowei, who wants to work in Liushenmen, takes the opportunity to worship Pan Tianzhu as his master. In the ridiculous daily teaching, the master and apprentice are constantly approaching the truth, and they are involved in a bizarre case from twenty years ago...