As strange phenomena descend upon the world and countless ghosts run rampant among the living, Ye Yu, an overworked office worker, unexpectedly transmigrates and binds himself to an Underworld Summoning System, becoming the Yin Heavenly Son. He summons underworld deities such as the Black and White Impermanence and Ox-Head and Horse-Face to rebuild order in the underworld, capture and punish evil supernatural entities, and guide departed souls into reincarnation. While protecting ordinary people, he cautiously probes and cooperates with human forces such as ghost tamers, joining hands with them to fight disaster-level supernatural entities and striving to restore peace and tranquility to the world.