Shin Sung-Rok portrays Kim Seo-Jin (Shin Sung-Rok), a man who is primarily concerned with achieving success in his personal life. It is because of his efforts that he is the youngest executive in his organization. In the company of his lovely violinist wife Kang Hyun-Chae (Nam Gyu-Ri) and a daughter, his life is ideal. When his young daughter is taken, his otherwise perfect existence comes to a grinding end. He sinks farther and deeper into despair. When his daughter is taken, he approaches Han Ae-Ri (Lee Se-Young), who was around one month in the past, in order to change the past. In addition to her academics, Han Ae-Ri works a part-time job to supplement her income and help pay for her sick mother's surgery. Her mother vanishes without a trace one day. When Kim Seo-Jin from the future encounters Han Ae-Ri, she goes into a state of despair.