Veteran investigator He Yuanhang and idealistic newcomer Ran Fangxu are drawn into a series of mysterious disappearances in Yuanlongli. What begins as an isolated case soon unravels into a complex web tied to an unsolved disappearance from eighteen years earlier. Clashing in method yet forced to rely on one another, the mentor–apprentice duo gradually forge a sharp partnership, pursuing buried truths and confronting the darkness behind each case as they work to bring justice to light.