In 1995 Berlin, after a woman who had spent the night with Michael Berg leaves his apartment abruptly, he watches a U-Bahn pass by, setting up a flashback to a tram in 1958. In the flashback, as a 15-year-old boy, Michael feels sick while wandering the streets. Pausing beside an apartment building, he vomits. A tram conductor named Hanna Schmitz who lives there, cleans him up and helps him return home. Michael, diagnosed with scarlet fever, recuperates at home until recovered, and then visits Hanna with flowers to thank her.
The 36-year-old Hanna seduces him, and they begin an affair. They spend much of their time together having sex in her apartment, after which she has had Michael read to her from literary works he is studying. After a bicycling trip with Michael, Hanna learns that she was promoted to a clerical job at the tram's head offices, upon which she suddenly leaves the company and her home, without telling Michael or anyone else where or why she has vanished.
In 1966, Michael is at Heidelberg University Law School. As part of a special seminar, the students observe a trial (similar to the Frankfurt Auschwitz Trials) of several former SS guards accused of letting 300 Jewish women and children perish in a burning church during the death march following one of the evacuation of concentration camps near Krakow, Poland. There Michael is stunned to see that Hanna is one of these defendants.
The key evidence in the trial is the testimony of Ilana Mather, author of a memoir relating how she and her mother Rose, who also testifies, survived. She describes how Hanna had women from the camp read to her in the evenings. Hanna, unlike her co-defendants, admits that Auschwitz was an extermination camp and that the 10 women she chose during each month's Selektion were gassed. She denied however, authorship of a report on the church fire event as an accident that could not be helped. Hanna's co-defendants then join together in a group lie to blame Hanna for writing the report. Hanna insists that all the guards present agreed on the contents of the report, but when asked to provide a handwriting sample, she admits the charge, instead of complying with the handwriting test.
Michael belatedly realizes Hanna's secret: She is illiterate, a fact she has been concealing all her life. Thus the other guards who blamed the written report on her can easily clear themselves. Michael informs the law professor of the favorable fact, but since the defendant herself has chosen not to disclose it, the professor is not sure what to do about it. Michael, appearing to visit Hanna, reneges and leaves the prison without seeing her.
Hanna receives a life sentence for her admitted leadership role in the church deaths, while the other defendants are sentenced to four years and three months each. Michael, meanwhile, engages in a romance with his classmate, whom he marries, and has a daughter with, but eventually divorces later. After retrieving his books from his childhood home from the time of his and Hanna's affair, he begins reading them into a tape recorder, which he then sends to Hanna. Eventually, she begins borrowing books from the prison library and teaches herself to read and write by following along with Michael's tapes. She starts writing back to Michael, first in brief, childlike notes, and as time goes by, her letters reflect her gradually improving literacy.
In 1988, a prison official telephones him to seek his help with Hanna's transition into society after her upcoming early release for good behavior. Since she has no family or other relations, he finds a place for her to live and even a job, and finally visits Hanna towards her release. During their meeting, Michael remains somewhat distant, inquiring about what she has learnt from her past, to which she replies merely "It doesn't matter what I feel and it doesn't matter what I think. The dead are still dead." Michael arrives at the prison on the date of Hanna's release with flowers, only to find out that Hanna has hanged herself. She has left a tea tin with cash inside and a note asking him to deposit the money in a bank account to Ilana, whose memoir of her dreadful experiences in the concentration camp Hanna has read.
Michael travels to New York City, where he meets Ilana and recounts his relationship with Hanna, and its long-lasting impact. He tells her about the suicide note and Hanna's illiteracy. Ilana rebuffs Michael there is nothing to be learned from the camps and refuses the money, and Michael suggests that it be donated to any Jewish welfare organization dealing with literacy. Ilana refuses any attempt at a conciliatory gesture, but claims the tea tin, describing it as similar to one stolen from her in Auschwitz.
The film ends with Michael driving his daughter Julia to Hanna's grave, and telling her their story.
Kate Winslet as Hanna Schmitz
Ralph Fiennes as the older Michael Berg
David Kross as the younger Michael Berg
Bruno Ganz as Professor Rohl, a Holocaust survivor
Alexandra Maria Lara as Ilana Mather, a concentration camp survivor
Lena Olin as Rose Mather (Ilana's mother), and as the older Ilana Mather
Vijessna Ferkic as Sophie, Michael's friend at school
Karoline Herfurth as Marthe, Michael's friend at university
Burghart Klaußner as the judge at Hanna's trial
Linda Bassett as Mrs. Brenner, prison official
Hannah Herzsprung as Julia, Michael Berg's daughter in 1995
Jeanette Hain as Brigitte, Michael's girlfriend in 1995
Susanne Lothar as Carla Berg, Michael's mother
Matthias Habich as Peter Berg, Michael's father
Florian Bartholomäi [de] as Thomas Berg, Michael's brother
Alissa Wilms as Emily Berg, Michael's sister
Sylvester Groth as the prosecutor at Hanna's trial
Fabian Busch as the defense lawyer at Hanna's trial
Volker Bruch as Dieter Spenz, a student in the seminar group
based on the 1995 German novel of the same name by Bernhard Schlink