Set in the dark days of 1945 during the Japanese colonial period, this gripping period thriller follows the desperate search for missing persons in the ominous city of Gyeongseong. When a mysterious spate of disappearances plagues the city, the pragmatic and resourceful Jang Tae-sang, played by Park Seo-joon, the owner of the city's most prestigious pawnshop, finds himself entangled in a deadly conspiracy. He is reluctantly joined by Yoon Chae-ok, portrayed by Han So-hee, a fierce and skilled investigator with a knack for tracking down missing people. Together, they venture into the terrifying depths of an underground hospital where a monstrous entity is being created from human suffering and scientific cruelty. The series masterfully blends historical drama with supernatural horror and creature features, exploring themes of humanity, sacrifice, and resistance against oppression. As Tae-sang and Chae-ok uncover the truth behind the disappearances, they must confront not only the physical horrors lurking in the shadows but also the moral compromises that survival demands.