Watch VoirFilms. After the sudden death of her husband, Ha-yeon is left in shock and quietly tries to return to everyday life. But an unexpected threatening phone call makes her feel that she is being watched. In a state of anxiety and isolation, Ha-yeon gradually finds comfort in Hyun-woo, the neighbor who lives upstairs. As details surrounding her husband's death begin to surface, she is drawn into an increasingly complex web of secrets and suspicion.