Introduction: During the Republic of China era, the populace was steeped in ignorance and superstition. Li Mudun, the finest carpenter in Fog City, is a master of the ancient text The Secret Manual of LuBan. It is said this manual is divided into two volumes: the first studies woodworking techniques, while the second contains mysterious and unfathomable occult arts. When brides vanish under mysterious circumstances, public suspicion falls on him. To clear his name, Li partners with detective Yang Zong and forensic expert Su Qingyun. Their investigation unveils murders staged with intricate "mechanical traps," leading them through a series of bizarre cases, from the ritual foundation sacrifice, the murderous puppet case, and the rickshaw puller case, all mysteriously linked to Li's estranged brother, Wu Xian. As the city descends into chaos following the death of a military governor, the trio must outwit Wu Xian in a final confrontation. Through their quest, they champion truth over ignorance, upholding the pragmatic spirit and rich heritage at the heart of Chinese tradition.