Ji-su, who struggles with borderline personality disorder, experiences a profound sense of emptiness and attempts suicide. During her hospital stay, she encounters Suk-won, a psychiatrist. Although Suk-won feels sympathy for Ji-su, he is unable to provide her with the assistance she needs. A year later, Suk-won unexpectedly crosses paths with Ji-su again and realizes she still requires support. This time, they develop a friendship rather than a doctor-patient dynamic. Through this new bond, Ji-su begins to heal from her past traumas. However, Suk-won becomes deeply infatuated with Ji-su, to the point where he cannot imagine life without her. His intense obsession leads him to a perilous brink when Ji-su decides to part ways with him.