One evening, Atticus tells the children that he is going out for a while. This usually means he is going for a walk, but he takes a light with him. Jem thinks something is up. When Aunt Alexandra goes to sleep, he and Scout summon Dill and the three of them go downtown. They find Atticus sitting outside the jail with his light on. Atticus has gone to keep watch at the jail to make sure no one comes to make trouble or cause any harm to Tom Robinson.
Before the children approach Atticus, they see four "dusty cars" driving up to the jail. A group of men, including Walter Cunningham Sr., emerge from the cars. They have come for Tom Robinson, presumably to do him harm or even kill him. Atticus is there (with help from Mr. Underwood) to prevent anyone from harming Tom. To this point, Atticus does not know the children have come downtown to find him at the jail. Scout and then Jem and Dill approach the group. She recognizes Walter but the other men are strangers to her. Atticus pleads with Jem to take Scout and Dill home. Jem refuses. Scout awkwardly befriends Walter and eventually he convinces the mob to go home.