Yanming Town, this small town may be shrouded in thick fog all year round. Detective Li Xunji came to this town because of a mysterious disappearance case. This case seems to be related to an ancient legend in the town. As the investigation deepens, Li Xunji discovers that the people in the town seem to be hiding something. Each resident has his own secret. Li Xunji discovers a series of clues that point to a historical event that has been forgotten by the people in the town. This event seems to be inextricably linked to the horror of the "Gray Mist Era".
