The drama is a romantic fantasy suspense drama that tells the story of Kim Seo-jin, who is devastated by the kidnapping of his young daughter, and a woman living in the past a month ago who fights alone to save the person she loves. After the two people living in the present and the past meet, they experience new truths and events each time in order to save the tragedy that has already happened. It is directed by Park Seung-woo, the director of "I'm Not a Robot" and "Spring is Coming, Spring", and written by Lee Soo-hyun.