France, 1944: As Paris has become too unsafe, 11-year-old Julien reluctantly returns to his boarding school after the Christmas vacations. Three pupils, including Julien's bunkmate Jean Bonnet, are new, but are teased and ridiculed by the other pupils. At first, Julien doesn't like Jean either, especially as he is an excellent student. But gradually a friendship develops between the two. The boys try to cope with their everyday lives, but the reality of war does not stop at the seemingly ideal world of the boarding school: food is scarce, the children are freezing miserably and during bombing raids, lessons are quickly moved to the cellars. Julien suspects that his new friend is hiding a secret: Jean is Jewish. One day, the Gestapo arrive at the door.