This scene occurs in Chapter 15 of the novel. Atticus sets his chair in front of Tom's jail cell to protect him from possible lynching from some of the townspeople who want to conduct vigilante justice against him. When Scout, Jem, and Dill follow Atticus (without his knowledge), Scout doesn't recognize the danger the armed men present and runs to Atticus. As Atticus tries to convince Jem to take Scout and Dill home, Scout surveys the crowd and recognizes Mr. Cunningham, the father of one of her classmates.

Scout says, "I sought once more for a familiar face, and at the center of the semi-circle I found one. 'Hey, Mr. Cunningham.' The man did not hear me, it seemed" (Lee 175). Scout goes on to make small talk with Mr. Cunningham about his legal "entailment" and encourages Mr. Cunningham to "Tell (Walter Jr.) hey for me, won't you?"

Scout doesn't directly convince Mr. Cunningham not to attack Atticus, but rather it seems that she reminds him that he's a father too, and Mr. Cunningham can't bring himself to harm Atticus in front of his own children. As Atticus reminds us in Chapter 16, "A mob's always made up of people, no matter what... you children last night made Walter Cunningham stand in my shoes for a minute. That was enough" (Lee 180).

While Mr. Cunningham came as a member of a lynch mob with the mentality of harming Tom and anyone (like Atticus) who got in his way, Scout reminds him that he's also a dad, and as he reconsiders from the role of a father, he can't bring himself to commit the intended violence.