Teenager Riona suffers from Persistent Genital Arousal Disorder, a condition causing uncontrollable sexual arousal without any stimulation. Merely seeing a man throws her into overwhelming sexual excitement, leading her to unconsciously engage in an intimate relationship with her older brother. As a result, she begins craving him daily, deepening their forbidden bond. The anguish and inner turmoil etched across the walls of their shared bathroom reveal the tragic nature of their love. Though her brother tries to protect her and showers her with affection, his efforts only drag them both into deeper despair. The story of her mysterious illness and their illicit relationship hurtles toward a shocking conclusion.