The Tree Demon of Black Mountain wrecked the three realms, and was later sealed by the four demon spirits symbiotic old and sick. The only person in the world, Pu Songling, can unlock the four seals by writing. Pu Songling writes "Painted Skin", "Ying Ning" and "Xiao Xie", opening the first three doors of the old and sick to release the Black Mountain avatar. When the Black Mountain doppelganger fought with the Heavenly Maiden, the Heavenly Maiden, who had disappeared in shape, was transformed with the help of Pu Songling's wife, Zhen Niang. Bring Pu Songling to the demon world to close the three doors.