In 2050, an organization called Alice was created to allow humans to travel through time and into parallel worlds. Everything changed when the “Book of Prophecy” was discovered—an ancient text that predicted the end of time travelers.

To keep the book from falling into the wrong hands, Alice sent agents Yoo Min Hyuk and Yoon Tae Yi back to 1992 to retrieve it from its last known guardian. During the mission, Tae Yi learned she was pregnant with Yoo Min Hyuk’s child. Choosing to raise the baby in secret, she changed her name to Park Sun Young and disappeared.

Years later, in 2020, their son Park Jin Gyeom becomes a successful detective. He meets a physics professor named Yoon Tae Yi—who looks exactly like his mother and specializes in quantum and time mechanics. Their meeting sets off a journey to uncover the secrets of the Book of Prophecy and their shared past.