The film begins with Bruno, portrayed by Asa Butterfield, who discovers that his father, Ralf (played by Ralf), a Nazi officer, has been assigned to oversee a concentration camp, a fact Bruno remains oblivious to at first. This revelation leads to a significant change in their lives as Bruno, accompanied by his mother Elsa (played by Elsa) and sister Gretel (played by Gretel), is uprooted from their home in Berlin and relocated to a place in modern-day Poland that is adjacent to the camp.
Upon arriving, Bruno is quickly restricted from venturing into the garden after his parents learn he can see the camp from there. Not only this, he and Gretel are assigned a personal tutor who actively promotes an antisemitic educational program, causing Gretel to grow increasingly aligned with the Nazi beliefs. However, Bruno's perspective remains untouched; he finds that the Jews he has been led to believe are monstrous do not, in reality, fit the stereotypes he has been taught.
In a moment of curiosity and defiance, Bruno disregards his parents' orders and goes exploring. This adventure leads him to the camp's fence, where he unexpectedly meets Shmuel, a boy of the same age, depicted by Jack Scanlon. Through their interactions, both boys come to realize their shared ignorance of the camp’s grim realities. As their friendship develops, Bruno often brings food to Shmuel, who later reveals that he is a Jew and has been imprisoned in the camp with his parents.
As the plot unfolds, Lieutenant Kotler brings tension into the narrative after he inadvertently discloses to Elsa the horrific truth behind the smoke rising from the camp—that it comes from the incineration of Jewish corpses. This confession leads Elsa to confront Ralf, heightening the film's emotional stakes. Just then, Kotler violently assaults Pavel, a Jewish servant, who is later replaced by Shmuel. When Bruno finds Shmuel again and offers him food, their encounter is disrupted by Kotler, who aggressively confronts Shmuel and demands to know how he obtained the food. Though Shmuel admits to receiving it from Bruno, out of fear, he denies it. The bruises on Shmuel's face during their next meeting suggest the ongoing brutality within the camp.
As the story progresses, Ralf informs Bruno and Gretel that they must move yet again to stay with another relative. Meanwhile, Shmuel is crushed by the loss of his father, who has gone missing in the camp, and in a gesture of friendship, Bruno promises to help him search for his father. On the day Bruno is set to be relocated, Shmuel gifts him a camp uniform, which prompts Bruno to slip through a gap in the fence and venture deeper into the camp, where he begins to uncover its chilling truth.
As Elsa notices Bruno's disappearance, a frantic search ensues. Sniffer dogs swiftly uncover Bruno’s clothes near the fence, unraveling the lurking horror. In a tragic turn, both boys unwittingly enter a gas chamber along with other prisoners, completely unaware of the fate that lies ahead until it is too late. In their final moments, Bruno and Shmuel hold hands, demonstrating their deep bond amidst chaos. Ralf becomes aware of the execution, calling out for his son in a moment of despair, while Elsa and Gretel collapse in anguish upon realizing the unspeakable tragedy that has unfolded. The final scenes starkly remember the devastating loss of life during the Holocaust, reminding audiences of the painful history that the film depicts.
