Yeon Seo majors in music at an university. She travels to Seoul to meet her older sister Jin Seo. When she arrives at her sister's house, Yeon Seo a large crowd and police there. Yeon Seo learns that her sister was found dead. The police concluded that her death was a suicide. Yeon Seo doubts her sister took her own life and begins to investigate. Detective Kim, impressed by Yeon Seo's efforts, reexamines the case.