Jung A-young, a theater and film student, experiences an ominous event when her protective amulet bracelet snaps just before the spring performance. Soon after, she begins suffering from unexplained fevers, exhaustion, and nights where she loses control of herself. The culprit? An 'incubus'—a being that feeds on human desire! To soothe these strange symptoms, A-young spends the night with her childhood friend, Kwon Seo-chan, and begins to rely on him. However, things get complicated when Kwon Yi-chan, Seo-chan's older brother and A-young's first love, returns to school, causing a subtle crack in their relationship. As emotions and confusion tangle, the influence of the incubus deepens, leading to an irreversible conflict between the brothers. Will the three of them be able to overcome their desires and the curse to find their own answers?