Because of the eradication of the criminal Lu Shiming, Inspector Gu Yuan was promoted to Chief Inspector, and Deputy Inspector Kang Yichen had no choice but to inherit the family business of Wanguan because of his father's death. The appearance of Lu Shijun, the new director of the Municipal Council, made the atmosphere of the patrol room solemn, because he was not only Lu Shiming's brother, but also Che Suwei's missing fiancé. It is unknown whether his appearance was to avenge Gu Yuan or to regain Che Suwei's heart. Kang Yichen held a socialite party in the mansion, but a woman died unexpectedly at the scene. According to Che Suwei's autopsy, the deceased died of heart failure, which was caused by a large number of parasites in the body, as if she was poisoned. According to the investigation, Gu Yuan found that the parasites were related to the special blood pendant on the neck of the deceased. The blood pendant is a luxury item that has become popular in the socialite circle recently, and its origin is unknown. Che Suwei discovered through clues that the blood pendant was related to the mysterious organization "Xinyuetang" and decided to go undercover to enter the old nest of Xinyuetang to find out.