Bruno, an eight-year-old boy from Berlin, is suddenly relocated to the countryside of occupied Poland after his father, Ralf, a high-ranking SS officer, receives a promotion. From his bedroom window, Bruno spots what he assumes is a farm behind his house, unaware it's actually an extermination camp. Despite his curiosity, his mother, Elsa, forbids him from exploring the back garden.
To further indoctrinate Bruno and his older sister Gretel, their father enlists the help of Herr Liszt, a tutor who promotes Nazi propaganda and antisemitism. Gretel becomes infatuated with Lieutenant Kurt Kotler, a young officer, deepening her alignment with the Nazi ideology. In contrast, Bruno is bewildered by the teachings, especially when he befriends Pavel, a Jewish doctor who has been forced into servitude after sustaining a minor injury.
Bruno's adventurous spirit leads him into the woods where he discovers a barbed wire fence enclosing the camp. Here, he meets Shmuel, another boy his age who shares that he is a Jew, taken to the camp with his parents. Their friendship blossoms as Bruno secretly brings him food during their encounters.
Things take a dark turn when Elsa overhears Kurt discussing the camp’s true horrors, including the scent of burning prisoners. Her confrontation with Ralf brings tension into their home, especially after a confrontation involving Kurt and Pavel turns violent. Bruno, unaware of these complexities, offers cake to Shmuel during a visit but later finds himself denying their friendship in front of Kurt, leading to Shmuel's absence for several days.
Eventually, as Bruno continues to visit the fence, Shmuel reappears, albeit injured. They reconcile and Bruno’s family experiences further turmoil when Ralf's mother, Nathalie, dies in an Allied bombing. As family tensions rise, Elsa voices her desire to move away from the camp, prompting Ralf to announce a plan to send the children to live with relatives until the war ends.
Before leaving, Bruno learns from Shmuel that his father is missing after a transfer and resolves to help find him. Shmuel provides Bruno with striped clothes to disguise himself as a prisoner. In a bid to sneak under the fence, their adventurous endeavor is abruptly interrupted by guards rounding them up.
Meanwhile, Gretel and Elsa are frantic when they discover Bruno is missing, leading to an urgent search. Unfortunately, Ralf's efforts culminate in a tragic discovery when he finds Bruno within the camp just as the prisoners are herded into a gas chamber. The horrific scene culminates in the death of both boys, leaving Ralf, Elsa, and Gretel to grapple with the profound loss and anguish that follows.
