In a partially deserted city, monsters roam. Christine does everything she can to protect her daughter Alex from this constant danger, going so far as to forbid her from going outside. But Alex has only one desire: to join her friends at the concert of her favorite band, despite the risk of running into a monster.

Margot and Marguerite are 12-year-old girls who seem no different from any other youngsters with the usual family and peer problems. While they appear to have similar faces and body shapes, they wear different clothes and hairstyles, but the biggest difference between them is that one lives in 1942 and the other in 2020. When the girls crawled into a wooden chest they were magically sent into each other’s timeline, and because the girls look so similar their family and friends do not notice the swap.