Spiritual Qi ebbs and flows and demonic tides begin to rise; Jiang Wan, a female employee at the Zhaojing Mortuary, collects demon corpses on the night shift and accidentally awakens the Sea of Consciousness Town-Demon Catalog. From then on, she slays demons to gather points and accumulates merit points, which are used to deduce cultivation techniques, break through realms, and strengthen. While investigating cases and advancing under the jurisdiction of the Demon-Town Bureau, she is caught up in the earth-shattering conspiracy between the demon race and ancient seals, ultimately becoming the person who guards the long night.