1990, Jeollanam-do. Twelve-year-old Iri trades a Coca-Cola mixed with bleach with a blue-eyed monk from Germany, believing it will let her die with her terminally ill twin, Chowon. Iri doesn't know it's a staged act by her shaman mother losing her divine power. But three months later, it is not Iri who dies, but Chowon. 2008, Berlin. studying abroad in Germany, Iri becomes an assistant writer and discovers an unfinished novel depicting a romance between the late Chowon and the blue-eyed monk. For the first time in 18 years, it is not Iri who asks the question—he does. "Why did you kill Chowon?"