The film opens in 1995 Berlin, where a dapper man named Michael Berg is in the midst of preparing breakfast for a young woman named Brigitte, played by Jeanette Hain, who stayed over. Their parting is awkward, and as Michael observes the passing Berlin S-Bahn, the story shifts back to early 1958 in Neustadt, West Germany. On a dreary, rainy winter day, a troubled teenage Michael, portrayed by David Kross, disembarks from a tram but soon finds himself wandering the streets until he halts in the doorway of an apartment building, where he becomes sick.
At this moment, Hanna Schmitz, the tram conductor, steps in to help him return home. Shortly thereafter, Michael is diagnosed with scarlet fever and must recuperate at home for three months, leaving him with little to do but contemplate his stamp collection.
As spring awakens, he decides to thank Hanna with a bouquet of flowers, leading her to invite him to accompany her to work on the tram line. However, when she catches him peering at her while she dresses, he flees in embarrassment. After a few days, he returns to apologize, and to his surprise, Hanna seduces him. Their relationship blossoms, and Michael visits her daily after school, even forsaking the attentions of girls his age. Their affair, confined to Hanna's apartment, revolves around literary readings, where she requests he read from various works he studies, including The Odyssey, The Lady with the Dog, and The Adventures of Huckleberry Finn.
Michael goes so far as to sell his treasured stamp collection so that they can embark on bicycle adventures in the countryside. But when Hanna is promoted to an office job, an unsettling change envelops her. On one of his visits, Michael attempts to read her Chekhov's The Lady with the Dog but is met with her sudden irritation. After their final encounter, Hanna leaves without divulging her new whereabouts, leaving Michael heartbroken.
Fast forward eight years to 1966: a 23-year-old Michael now studies at Heidelberg Law School. He attends a seminar led by Professor Rohl, a former concentration camp survivor, where he witnesses a gripping trial of women accused of letting 300 Jewish women perish in a church fire during the horrifying Death marches that followed the 1944 evacuation of Auschwitz. To Michael's shock, he discovers that Hanna is among the defendants. This revelation sends him into a soul-searching journey as he grapples with her past at a former camp.
The trial ignites intense debate among the seminar students, with some asserting that the events serve no purpose other than highlighting the abyss of evil. Key evidence emerges from Ilana Mather, a Jewish woman (played by Alexandra Maria Lara), who recounts her harrowing experiences during the Holocaust. When Hanna takes the stand, she shockingly acknowledges her awareness of Auschwitz's true nature, her admission laying bare the grim reality of her actions as an SS guard. She candidly reveals that she selected ten weaker prisoners each time to be executed for the sake of processing new arrivals, all while demanding that her victims read to her.
The tension escalates when it is revealed that 300 counts of murder stemmed from a tragedy in which Hanna and her fellow guards locked church doors during an aerial bombing, leading to a devastating inferno. Despite the mounting evidence, Hanna adamantly denies her involvement until faced with a document bearing her signature. In that moment, the truth crystallizes for Michael: Hanna is illiterate, and many of her choices—including her affiliation with the SS—were made to obscure this fact.
With profound conflict, Michael realizes he possesses knowledge that could aid one of the defendants yet feels torn over revealing it. Hanna ultimately receives a life sentence while her co-defendants face significantly lighter penalties. Following his graduation, Michael marries Marthe and has a daughter named Julia but remains emotionally distant, leading to the dissolution of his marriage.
Years later, he reconnects with Hanna by sending her audio tapes of literary works that help her teach herself to read. As Michael drifts further from his family, he receives a letter from the prison warden regarding Hanna’s impending release on parole. Reluctantly, he agrees to support her upon her release, finds her a place to live, and secures a job for her. However, during their awkward reunion, Hanna, burdened by memories of her past, reveals her harrowing realizations about her actions during the war. Tragically, Michael's visit ends in despair, as Hanna takes her life shortly after his departure, leaving him a note and a tea tin filled with her savings.
The narrative concludes with Michael's journey to New York, where he confesses his past with Hanna to Ilana. He reveals Hanna's illiteracy and expresses his desire to honor her last wishes by donating her savings to support an organization combatting adult illiteracy. Ultimately, Michael revisits Hanna's grave with his now adult daughter, Julia, beginning to share the intricate and painful story of their shared past.
