The story is told in three parts by the main character, Michael Berg. Each part takes place in a different time period in the past.
Part I begins in an unnamed German city (Heidelberg) in 1958. After 15-year-old Michael becomes ill on his way home, 36-year-old tram conductor Hanna Schmitz brings him to her apartment and cleans him up before bringing him to his parents. He spends the next several months absent from school battling a pre-existing case of hepatitis.
On a subsequent visit to thank her for her help, he realizes he is attracted to her; embarrassed after she catches him watching her get dressed, he runs away, but he returns at a later date. After she asks his help retrieving coal from downstairs, he becomes dirty and she bathes him; afterwards, they make love. He begins returning to her apartment on a regular basis, and the two take part in an affair. They develop a ritual of bathing and making love, before which she frequently has him read aloud to her, chiefly from works of German literature. Both remain somewhat distant from each other emotionally despite their physical closeness. Hanna also is at times physically and verbally abusive to Michael.
Months later, Hanna suddenly leaves without a trace. The distance between the two of them had grown while Michael spent more time with his school friends, and so he feels guilty and believes it was something he did that caused her departure. The memory of Hanna taints all his other relationships with women.
In Part II, eight years later, while attending law school, he is part of a group of students observing a war crimes trial. A group of middle-aged women who had served as guards at a satellite of Auschwitz near Cracow are being tried for allowing Jewish women under their ostensible protection to die in a fire at a church that had been bombed during the evacuation of the camp. The incident had been chronicled in a book written by one of the few survivors, who emigrated to America after the war; she is the star witness at the trial.
To Michael's surprise, Hanna is one of the defendants. This sends him on a roller coaster of complicated emotions. He feels guilty for having loved a criminal and is also mystified at Hanna's willingness to accept full responsibility for having supervised the other guards despite evidence proving otherwise. During the trial, Michael realizes that all her life Hanna has been protecting what is to her a more terrible secret than her Nazi past: she cannot read or write. This inability shaped all her actions, her original refusal of the promotion that put her in the position to directly kill these people, and also her panic the rest of her life over being discovered. During the trial, it comes out that she took the weak and sickly women and had them read to her before they were sent to the gas chambers, Michael decides she wanted to make their last days bearable, he later decides she sends them to the chambers so they won't reveal her secret. The reader is left to interpret her motives. She is convicted and sentenced to life in prison.
During Part III, Michael, trying to come to terms of his feelings for her, begins taping readings of books and sending them to her with no correspondence. Eventually she learns to read by borrowing the corresponding books from the prison library and reading along. She writes back to him, but he does not reply. When Hanna is soon due to be released, he agrees to help find her a place to stay as well as gainful employment. Many years have passed and he is divorced and has a daughter from his brief marriage.
On the day before her release in 1984, and following a long-delayed visit from Michael, she commits suicide. Michael learns from the warden that she had been reading books by many prominent Holocaust survivors, such as Elie Wiesel, Primo Levi, Tadeusz Borowski, and histories of the camps. The warden is angry with him for not communicating with her in any way other than the audio tapes.
At the end of the novel Michael visits the Jewish woman who wrote the book about the death march from Auschwitz and is now living in New York. She points out, for the first time in the story, how inappropriate their relationship was, and how it damaged him, and draws parallels to Hanna's treatment of the poor and the weak at the camp (which ring true). She asks /tells him how he must have had a short, unloving marriage (true) that resulted in a child who was away from him (also true). She refuses to take the money, saying "[Hanna] cannot buy my forgiveness so cheaply" and tells him to donate it to a Jewish charity of his choice. He chooses one that focuses on combating adult illiteracy. The woman does, however, take the old tin tea box where Hanna had kept her papers and mementos, "to replace the similar tea box which she herself had until being sent to the camp" - a small ambiguous gesture towards her former guard. After that meeting, Michael goes to visit Hanna's grave for the first and only time.
When this movie came out, it was criticized severely by some prominent people. Somehow I feel the criticisms are not legitimate. The Holocaust, like any event of enormous influence on the world, is not a simplistic black and white, good and bad story. And it cannot, should not be treated as out of bounds for any type of conversation ouside of one that is driven by malice or intolerance. I certainly don't believe that Schlink's motives were suspect.
Schlink's problematic approach toward Hanna's culpability in the Final Solution has been a frequent complaint about the book. Early on he was accused of revising or falsifying history. In the Süddeutsche Zeitung, Jeremy Adler accused him of "cultural pornography" and said the novel simplifies history and compels its readers to identify with the perpetrators.
In the English-speaking world, Cynthia Ozick called it a "product, conscious or not, of a desire to divert (attention) from the culpability of a normally educated population in a nation famed for Kultur." Frederick Raphael was blunter, saying no one could recommend the book "without having a tin ear for fiction and a blind eye for evil."
Interestingly, Schlink has said, most of the criticism he hears and reads over Michael's inability to fully condemn Hanna comes from those closer to his own age. Older generations, he said, that lived through those times are less critical, regardless of how they actually experienced them.