The little boys whose innocent friendship forms the central plot of the story are named Bruno and Shmuel. Bruno is the nine year old child of a Nazi commandant, and Shmuel is a young Jewish inmate in one of Hitler's death camps, Auschwitz, or as Bruno's young ears hears it, "Out-with". Visiting at the fence one day, the boys discover that they share the same birthday and have other things in common. Although Bruno can't comprehend exactly what is happening in his family's home, he knows enough to know that he doesn't like the man called "the Fury" (the Fuhrer) who comes to dinner one evening. Bruno spends most of his time exploring the woods around his family's quarters, and meeting to converse with his friend. The two are annoyed that they can't play games together because of the prison fence.
Their lack of awareness of the reasons they shouldn't play together leads them to hatch a plan so that they might; Shmuel smuggles a pair of striped pajamas through the fence to his buddy, who puts them on, and heads into the camp through the fence.