In a quiet and remote convent in South Korea, a group of nuns lives under the strict watch of the mother superior, who has kept a dark family legacy a secret for centuries. With the arrival of a new postulant, their lives take an unexpected turn. The young woman, with a tumultuous past and a rebellious spirit, begins to uncover mysterious letters hidden in the convent's library and a series of rituals that seem to be connected to ancient legends of witchcraft.
As she delves deeper into these secrets, she unleashes supernatural forces that have been trapped for generations. The convent, once a home of peace, turns into a battleground between good and evil, where the nuns must face their own shadows. Among them, some begin to manifest hidden abilities, revealing that not all are what they seem.
With each revelation, the new postulant not only challenges the norms of the community but also has to confront the demons of her own past. Tension mounts when a series of terrifying events unfold, forcing the nuns to unite to combat the threat they have awakened. Amid the confusion, they question their faith, loyalties, and what it truly means to be part of a sisterhood. A final battle looms, where not only their lives but also their souls are at stake. The darkness lurking in the corners of the convent is not the only thing they fear; sometimes, the most dangerous enemy is closer than they think.