The "ghost ship" entered the port. In order to protect himself, the boss wanted to hastily close the case as a "water bandit riot", but Di Renjie felt that something was wrong. The ceremony was imminent, and the people of Chang'an City were in a panic. The queen ordered Shen Ming, the chief of the Dali Temple, to close the case within three days. Shen Ming had to put the pressure on Di Renjie to solve the case. Leng Jiyue, the chief of the water supervision, also joined in, and met his old acquaintance Duan Yan on the "ghost ship" where the case occurred. The three went to the "lower city" of Chang'an Intelligence Center to obtain intelligence. After exploring all the way, they finally found the secret hiding place - Yunku, which was the place where the two major underground forces in Chang'an were found. Di Renjie and others entered the ancient mausoleum Yunku, broke the traps and fell into despair. Di Renjie relied on soil layer identification to find a way out, and finally broke through the Yang Tomb and found the Yin Tomb where King Huai and the descendants of Dayue raised Long Ao. The truth gradually surfaced. The ceremony was imminent, and various dark forces were waiting for an opportunity to move, and Di Renjie had already seen through the slightest detail and laid a net...