Strange murder cases are occurring one after another in Jiangcheng. In a wife-murder case, the killer uses secret alchemical techniques to conceal all traces. In a drowning case, the victim is carefully framed. And behind the haunting rumors surrounding an abandoned village lies a drug-manufacturing den. Wu Heng, an apprentice constable, is entrusted with a critical mission. Armed with criminal psychology knowledge far ahead of his era and autopsy skills granted by a mysterious system, he searches for clues in the smallest details, unraveling the truth behind each case. Every seemingly flawless crime scene conceals a fatal mistake made by the culprit, and every thrilling manhunt uncovers another layer of darkness lurking beneath the city.