Kim Seo-jin (Shin Sung-rok) is a successful and workaholic construction company director. One day, his daughter goes missing with no trace. Shortly after, his wife, Kang Hyun-chae (Nam Gyu-ri), commits suicide due to the shock. Han Ae-ri (Lee Se-young) is a hard-working daughter whose mother goes missing in a hospital. She then receives a phone call from Seo-jin. He lives one month ahead of Ae-ri. He asks her to prevent the horrific events that destroyed his family and in return, she wants him to find her mother.