Chen Haoyu, a down-and-out young Daoist priest, originally just wanted to look after his dilapidated temple and scrape together enough to get by. Unexpectedly, an accident awakened a mysterious supreme treasure known as the Heaven and Earth Demon-Slaying Diagram, setting him on the path of slaying demons and vanquishing evil. To escape the pursuit of the Demon-Suppression Bureau, he disguises himself and sneaks into Qingzhou. There, however, he discovers that behind the city's prosperity, demons run rampant, corrupt officials collude with evil forces, and ordinary people have become nothing more than prey for bloodthirsty monsters. While pretending to be poor and weak, Li Ping'an secretly uses thunder techniques to exterminate demons and outwit the powerful. Together with Huang Laosan, he gradually uncovers the shocking conspiracy lurking behind Qingzhou and rediscovers the Dao his master left behind for him amid the chaos of a troubled age.