Bruno is a 9 year old boy growing up during World War II in Berlin, Germany.[3] He lives in a huge house with his loving parents, his twelve-year-old sister Gretel (whom he refers to as a Hopeless Case), and maidservants. His father is a high-ranking SS officer who, after a visit from Adolf Hitler (referred to in the novel as "The Fury", Bruno's misrecognition of the word "Führer") and Eva Braun, is promoted to Commandant, and to Bruno's dismay, the family has to move away to a place called "Out-With" (in reality the Auschwitz Concentration Camp)

Bruno finds out he is not allowed to explore the back of the house or its surroundings. Out of boredom and curiosity, he decides to explore anyway. Whilst poking about he spots a boy on the other side of the fence. Excited that there might be a boy his age, Bruno introduces himself and finds out the Jewish boy's name is Shmuel. Shmuel and his family were brought here, separated from each other and forced to work. Almost every day, the two boys meet at the same spot. Soon, due to their remarkable similarities they become best friends. Despite their differences of circumstance, they are able to understand one another on a deeper level. This empathy fundamentally calls into question the difference between an 'undesirable' Polish Jew and a German. Over the course of the book, Bruno shows a great deal of naïvete, whilst Shmuel seems to have more knowledge, as he has had first-hand exposure to the suffering in the death camp.

Bruno's mother persuades his father to take them back to Berlin, with Bruno's father staying at Auschwitz as the commandant. Though Bruno is about to go back to Berlin with his mother and sister, as a final adventure, he agrees to dress in a set of striped pyjamas to go under the fence to help Shmuel. As Bruno had recently had his head shaved because of a lice infestation, his outward appearence is