The story takes place in the Ming Dynasty. The emperor (Song Yuncheng) is seriously ill and in a coma, and the throne is undecided. This incident has caused panic in the court. At this juncture, a serial murder case occurred in the capital. The court commissioned the six gates of the capital to investigate the case, catch the murderer, and appease the people's grievances. Shen Zimu (Huang Wenhao) is the leader of the six gates. He knows that the strangeness of this case will inevitably implicate the palace walls. He wanted to hastily close the case, but he didn't expect his son Shen Lixing (Lin Feng) to be involved. With the cooperation of father and son, the case came to light, but it also made the crimes committed by the queen resurface. Shen Zimu was assassinated. In grief, Shen Lixing reported the whole story to the awakened emperor, causing the throne to fall into the hands of King Qi (Alex Fong). By chance, Shen Lixing discovered that his father's death was related to King Qi. This person was extremely insidious and cunning, and was the real black hand behind the incident.