She Jun, an ancient snake who has slept for a millennium, is awakened by modern equipment. She Jun thereby becomes a special consultant to the Demon Management Bureau, originally intending only to slack off, punch the clock, collect a subsidy, and live a leisurely little life of drinking tea and sunbathing. But sudden changes strike unexpectedly; the Zhenlong Well used in the early Ming Dynasty to suppress evil spirits is accidentally dug up, the seal shatters, the powerful Lord of Filth breaks the seal and emerges, and the entire capital faces the threat of destruction.