In To Kill a Mockingbird, Chapter 17 begins with Scout and Jem walking to the courthouse with their father, Atticus, for Tom Robinson's trial. Scout is excited to go to the courthouse because she has never been inside before, and she is curious about what will happen.
As they walk, Atticus explains to Scout and Jem that the trial will be difficult because Tom is a black man accused of raping a white woman. Atticus tells them that it is important to be fair and objective in the face of such a difficult and emotional case.
When they arrive at the courthouse, Scout is amazed by the size and grandeur of the building. Inside, they find that the courtroom is packed with people, and Atticus has to push his way through the crowd to get to his seat.
The trial begins with the prosecution's witness, Mayella Ewell, taking the stand. Mayella testifies that Tom Robinson attacked and raped her, but Atticus is able to expose several inconsistencies in her story. He also points out that Mayella has bruises on her face, which suggest that she was beaten by someone.
In Chapter 18, the defense continues its case by calling Tom Robinson to the stand. Tom testifies that he did go to Mayella's house to do some work, but that he did not attack or rape her. He claims that Mayella made advances towards him, and that he ran away when her father, Bob Ewell, came home and saw them together.
In Chapter 19, the trial comes to a close and the jury begins to deliberate. Scout and Jem are anxious to know the outcome, and they worry that Tom will be found guilty despite the lack of evidence against him.
In Chapter 20, the jury returns a verdict of guilty, and Tom Robinson is sentenced to life in prison. Atticus is disappointed but not surprised by the verdict, and he tells Scout and Jem that sometimes the truth does not matter in a court of law.
Despite the outcome of the trial, Atticus is proud of the way he defended Tom and stood up for what he believed was right. He tells Scout and Jem that it is important to always do what is right, even when it is difficult or unpopular.