There is a "yin realm" under the surface world of modern cities, which is condensed by resentment, obsession, and yin energy. Abandoned hospitals, morgues, old houses and other places where Yin energy gathers form closed copies of the Yin world every night. The ancestral master's Taoism is divided into nine levels of inheritance. Every time a ghost is killed or a calamity is experienced, one level is awakened. The four major categories of spells, seals, mantras, and magical instruments, the boundary between the living and the dead, the dialectics of resentment and redemption, and the fear and courage of ordinary people facing supernatural forces
