When the four cars approach the jail, Scout notes that Atticus "seemed to be expecting them." Atticus is calm and even friendly to the men when they ask about Tom. It isn't until Scout, Jem, and Dill approach that Atticus expresses signs of fear. He still tries to maintain his calm but now he is uneasy with the situation:
Atticus got up from his chair, but he was moving slowly, like an old man. He put the newspaper down very carefully, adjusting its creases with lingering fingers. They were trembling a little.
Still calm, but determined, Atticus tells Jem to take Scout and Dill home. Atticus is quite prepared to deal with these men, but with any potential for violence, he doesn't want the children anywhere in the area. Jem is defiant. Atticus, still calm and reasonable, asks him repeatedly to take them home. Scout intervenes by befriending Walter Cunningham, Sr. He eventually convinces the men to go home. Atticus, although scared at times, remained calm because he knew that was the best way to deal with the situation. Shouting, scolding, or inciting the men would only provoke them. He also knew that Mr. Underwood was upstairs with a shotgun to protect him. But when the children show up, he becomes uneasy because of all the potential violence in the area: the mob of men and the gun. On their walk home, Atticus is relieved and maybe even proud of his children.
As they passed under a streetlight, Atticus reached out and massaged Jem’s hair, his one gesture of affection.