Her life began with misfortune. Ever since she woke up in a hospital bed at the age of twenty with no memory, and saw things she shouldn't have seen on her way home, Seo Yi-yeon was desperate in everything she did. To get better, to become ordinary, and not to die of loneliness. After years of effort, the countless cracks in her life were finally about to be covered in dust and forgotten. But— "Have you ever lost something important?" On her twenty-ninth birthday, a mysterious man appears before her, and Yi-yeon's once-peaceful daily life begins to be shaken once again.