After the events of Wonder, Julian has left Beecher Prep for good. He is visited by Sara, his grandmother from Paris, who, in response to Julian’s reflection about his need to be socially passive to fit in at his new school, tells him about her childhood as a young Jewish girl in Nazi-occupied France during World War II.
In 1942, Sara evades being rounded up by the Gestapo and spends over a year being hidden by her classmate Julien (one of whose legs is paralyzed as a result of poliomyelitis) in a barn adjacent to the house he lives in with his parents. She is instructed never to leave the structure to avoid being discovered by their neighbors whom they suspect of being Gestapo or Milice informers. At night, Julien teaches Sara what he has learned at school during the day. The affection between them eventually grows into love.
In 1944, after the liberation of Monte Cassino, Julien is arrested by the Milice on his way to school at a checkpoint and forcefully transported to a remote camp in the mountains via lorry. During an escape attempt by the other prisoners, he is shot dead. At the end of the war, Sara is reunited with her father, Max, but she learns her mother has been killed at Auschwitz. Sometime later, Max accepts a new job in Paris, and he and Sara move there, but she still makes sure to preserve her friendship with the Beaumiers and visit them often.
Back in the present, Julian, moved by his grandmother’s story, decides to make amends with his past and become a better person.