Atticus goes to the Maycomb Jail at night to sit out front and guard Tom Robinson, who has been transferred there, from being lynched. Jem and Scout are worried, and with Dill, they go to the jail, arriving just as cars filled with the men who have come to lynch Tom pull up.
The scene is tense as the children burst into the middle of it. Their presence there frightens Atticus, who fears that they will be hurt by the mob. However, the children manage to defuse the situation and help prevent a lynching.
Scout notes that the group of men has been changed so entirely by their mob mentality that they seem like strangers to her. However, when she kicks one who picks up Jem by the collar and threatens him and then engages Mr. Cunningham in conversation, the group starts to revert back to acting like ordinary humans.
Scout tells Mr. Cunningham about his son, Walter, coming over for dinner at her house one night and her beating Walter up once, but there being no hard feelings between them. She says, "Tell him hey for me, won’t you?" She also talks to Mr. Cunningham about his entailments.
Mr. Cunningham suddenly realizes he is threatening the father of a real person, and his buildup of rage begins to defuse. Scout recounts,
He squatted down and took me by both shoulders. “I’ll tell him you said hey, little lady,” he said. Then he straightened up and waved a big paw. “Let’s clear out,” he called. “Let’s get going, boys.”
At this, the men disperse, getting back into their cars and driving off.
Scout's ability to connect with one of the men on a human level diverts a lynching and the violence that would have erupted had the men tried to break into the jail. We find out that not only was Atticus guarding the place, but Mr. Underwood was standing by with his shotgun in the newspaper office nearby. There is no telling who might have gotten hurt had the children not shown up.