The Reader

Berlin in 1995. Michael Berg watches an U-Bahn pass byâthen flashing back to a tram in 1958 Neustadt. A 15-year-old Michael (David Kross) gets off because he feels sick and wanders the streets, pausing in the entryway of a nearby apartment building where he vomits. Hanna Schmitz (Kate Winslet), a tram conductor, comes in and helps him return home.
Michael, diagnosed with scarlet fever, rests at home for the next three months. After he recovers, he 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 she has had Michael read to her from literary works he is studying. After a bicycling trip, Hanna learns she is being promoted to a clerical job at the tram company. She abruptly moves without telling Michael.
In 1966 Michael is at Heidelberg University law school. As part of a seminar, the students observe a trial (similar to the Frankfurt Auschwitz Trials) of several women accused of letting 300 Jewish women die in a burning church when they were SS guards on the death march following the 1944 evacuation of a concentration camp near Krakow. Michael is stunned that Hanna is one of the defendants.
In the trial the key evidence is the testimony of Ilana Mather (Alexandra Maria Lara), author of a memoir of how she and her mother (Lena Olin), 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 ten women she chose during each month's Selektion were gassed. She denies authorship of a report on the church fire, despite pressure from the other defendants, but then admits it rather than complying with a demand to provide a handwriting sample.
Michael realizes Hanna's secret: she is illiterate and has concealed it her whole life. The other guards who claim she wrote the report are lying to place responsibility on Hanna. Michael informs the professor that he has information favourable to one of the defendants but is not sure what to do since the defendant herself chose not to disclose the information. Michael arranges a visit with Hanna in prison, but once there he leaves 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 (Ralph Fiennes) meanwhile marries, has a daughter, and divorces. Retrieving his books from the time of the affair with Hanna, he begins reading them into a tape recorder. He sends the cassette tapes and a recorder to Hanna. Eventually, she begins to check the books out from the prison library and teaches herself to read and write by following along with Michael's tapes. She starts writing back to Michael in brief, childlike notes, asking him to write to her. As time goes on, the letters reflect her gradually improving literacy.
Michael does not write back or visit but continues simply sending tapes, and in 1988 a prison official (Linda Bassett) telephones him to seek his help with Hanna's transition into society after her upcoming early release due to good behavior. He finds a place for her to live and a job and finally visits Hanna a week before her release. In their meeting, Michael remains somewhat distant and confronts her about what she has learned from her past, to which she replies "It doesn't matter what I feel. It doesn't matter what I think. The dead are still dead.", seemingly disappointing him. Michael arrives at the prison on the date of Hanna's release with flowers only to discover that Hanna hanged herself. She has left a tea tin with cash in it with a note asking Michael to give the cash and money in a bank account to Ilana. He discovers that she killed herself after reading Ilana's memoir of her horrifying experience in the concentration camp.
Michael travels to New York City where he meets Ilana (now Lena Olin) and confesses his relationship with Hanna. He tells her about the suicide note and Hanna's illiteracy. Ilana tells Michael there is nothing to be learned from the camps and refuses the money. Michael suggests that she donate the money to an organization that combats adult illiteracy, preferably a Jewish one. She wants him to take care of this instead. Ilana keeps the tea tin since it is similar to one stolen from her in Auschwitz.
Michael drives Julia, his daughter, to Hanna's grave and tells her their story.

Question: What is the key evidence in the trial?
Answer: testimony of Ilana Mather