Part 1: Yoon Tae Yi and Yoo Min Hyuk time travel from 2050 to 1992 and recover the "Book of Prophecy," a book that reveals the tragic end of time travel. However, Tae Yi finds out she is pregnant and decides to stay and have the baby by herself. She changes her name to Park Sun Young and gives birth to Jin Gyeom, a boy who grows up lacking pro-social emotions. Part 2: After celebrating his mother's birthday, Jin Gyeom finds his mother dying on the floor. Her death hits Jin Gyeom hard, and he decides to become a police officer. Now in 2020, Lieutenant Park Jin Gyeom takes on a case where a kidnapped child claims she was with her mother from the future.