A young boy Hee-Joon is possessed by an evil spirit. Sister Julia, driven by her faith and compassion, takes it upon herself to save the boy, while Sister Michaela, initially sceptical, is drawn into the investigation. As they delve deeper into the mystery, they encounter a series of chilling events and uncover a dark secret hidden within the walls of their convent. The nuns must confront their own fears and beliefs as they battle against the powerful evil that threatens Hee-joon’s life and the sanctity of their order.