The modern forensic doctor Shen Mo transmigrates by accident and becomes a county magistrate in the fictional Great Sheng dynasty, one who was demoted and died in office. After waking, he uses his exceptional powers of observation and forensic knowledge to solve a string of bizarre cases, including the “Oleander Poisoner” and the “Bloodstained Garment Mystery.” His fame soon rises, earning the admiration of the virtuous Prince Rui, who promotes him to Imperial Inspection Envoy.
From then on, Shen Mo forms a team with his guard Zhao Hu and the physician Su Banxia, traveling throughout the land. They solve one cold case after another: from the official corruption behind the “Macheng Wife Murder” to the elaborate frame-up in “The Accursed Poem Fan,” from the chain of wrongful convictions at “Qijian Bridge” to the execution-ground conspiracy behind “The Death Row Prisoner's Return.” Yet Shen Mo gradually discovers that behind countless cases lurks a vast organization called the Netherworld Bureau. It has infiltrated the government and manipulated the justice system, with the aim of destabilizing the dynasty.
As the investigation grows more perilous, Shen Mo's team is repeatedly ambushed, and at one point he is even accused of being a spy. In the end, all the clues point to the emperor's highly respected uncle. At the imperial court, Shen Mo uses irrefutable evidence and eloquent arguments to expose his true face, foil the coup, and destroy the Netherworld Bureau.
After accomplishing his mission, Shen Mo declines high office and generous rewards, choosing instead to continue traveling through the land with his companions. Their carriage heads into the distance, where new cases and legends still await this immortal magistrate-investigator.
