Simon's 9th grade class has organized a school trip to Struthof, the only Nazi concentration camp on French soil, They need chaperones, so Simon asks his grandmother, Rose, if she would come. The trip becomes an opportunity for her to delve into the dark and harsh part of their history that was forced upon the family but that no one has ever dared discussed. And it is through her mother, Mathilde's old photo albums and detailed diaries that Rose and her grandson will uncover a terrible family drama...