As Chapter 15 of Harper Lee's To Kill a Mockingbird begins, the Finch family is interrupted by the sudden, unannounced arrival of a group of men, a development that Lee's young narrator, Scout, views as particularly ominous, noting that such assemblages only occur for one of two reasons: death and politics. There is, Scout will learn, a third reason: her father Atticus' decision to defend an African American, Tom Robinson, accused of raping a white woman--a serious allegation in the American South of the 1930s. Sensing potential danger, Atticus orders his children to stay inside the house.
The approaching trial of Tom Robinson provides To Kill a Mockingbird's most enduring and important theme. Race relations across the South, as well as in much of the United States, were abysmal, with blacks still struggling to be accepted as American citizens on the same level as the nation's Caucasian majority. The fictional town of Maycomb, Alabama, the setting for Lee's novel, is a microcosm of the region at large. Atticus Finch, as we know, is a paragon of virtue who is raising Scout and her older brother Jem with certain values that makes this particular family far more accepting of racial diversity that most of their neighbors. Scout and Jem's aunt, Alexandra, is more socially refined than many of the characters who populate this story, but she is no less judgmental and, her in own way, racist. When Scout protests Aunt Alexandra's order that the young girl stay away from her classmate Walter Cunningham, the older woman responds, "Because--he--is--trash. . ."
Aunt Alexandra's judgmental nature, as noted, extends to her views on race. It is not, therefore, surprising that she is upset over Atticus' decision to defend Tom Robinson. Arriving home one day to discover that Atticus and Alexandra, brother and sister, had been arguing again, Jem explains the situation to Scout:
“She won’t let him alone about Tom Robinson. She almost said Atticus was disgracin‘ the family. Scout... I’m scared.”
Alexandra is farther up the socioeconomic ladder than the Bob Ewells of Maycomb, but she is no less prejudiced in her views. Additionally, she clearly lacks her brother's physical and moral courage. While Alexandra is racist, however, she is also concerned about her brother's welfare and fears for his safety.