Nuremberg, 1938: On the night of Kristallnacht, eleven-year-old Lisavet Levy is hidden by her father from approaching forces in a mysterious place called the time space, a library where all the memories of the past are stored inside of books. When her father doesn't return for her, she becomes trapped, spending her adolescence walking through the memories of those who lived before. When she discovers that living timekeepers are entering the time space to destroy memories and maintain their preferred version of history, Lisavet sets about trying to salvage the past, creating her own book of lost memories. Until one day in 1949, when she meets an American timekeeper named Ernest Duquesne, who is intent on keeping her from her task. What ensues sets her on a course to change history and the time space itself forever.

Boston, 1965: Amelia Duquesne is mourning the death of her uncle and guardian, Ernest, when she's approached by Moira, the enigmatic head of the CIA's highly secretive Temporal Reconnaissance Program. Moira tells her about the existence of the time space-accessed only by specially designed watches whose intricate mechanisms have been lost to time-and enlists her help in recovering a strange book her uncle had once sought. But Amelia quickly realizes that the past-and the truth-are not as straightforward as Moira would like her to believe.

A sweeping, cinematic love story, this feat of imagination explores memory, time, and the lengths we will go to in order to protect the existence of those we love.