Twenty years prior to the series, Soo-min and his father, along with priest Moon Ki-seon, witnessed the death of his mother at a young age, where she was possessed and killed by a demon due to his father's refusal to believe in exorcism preventing her from receiving one.
Dua puluh tahun sebelumnya, Soo-min dan ayahnya, bersama dengan pendeta Moon Ki-seon, menyaksikan kematian ibunya di usia muda, di mana dia dirasuki dan dibunuh oleh setan karena penolakan ayahnya untuk percaya pada pengusiran setan.