Chapter 15 of To Kill A Mockingbird is a pivotal chapter as what happens in this setting affects the trial of Tom Robinson, and also points to the integrity of Atticus and the maturation of Jem. For, in this chapter, there are two scenes which involve men who have come to talk to Atticus with the intent of persuading him to take a certain action. In both cases Atticus stands against the mob.
First, a group of men come to the Finch home because they want to discuss what is to be done with Tom Robinson, hoping to move him. Sheriff Tate wants to transfer him to the county jail, but Atticus thinks the idea foolish, advising Tate that the trial will be the next day, so Tom only needs to stay overnight in the town jail.
Without expressing his own concern, Atticus announces that evening that he is going out for a while, but when he does not return by ten o'clock, Jem dresses to go to town; Scout insists upon accompanying him, fortuitously, as it turns out. For, it is Scout's personal address to Mr. Cunningham that makes this man realize that he is hostilely confronting Atticus Finch, a father and a man who has been generous with him in allowing him to pay for legal services with food. As a result, he calls off the Old Sarum Bunch and they drive away, abandoning their intention to force Atticus to give them Robinson so they can lynch him.
The scene at the jail is the highest moment of tension in the plot. Atticus is nervous, but maintains his composure, Jem is frightened for his father, and Mr. Underwood prepares for conflict as he aims his rifle at the jailhouse door in anticipation of the mob getting past Atticus. Innocent Scout who diffuses the tension does not realize the potential for crisis.