Most importantly, the Halloween adventures that take place in Chapter 28 serve as the climax to the novel. I'm sure Harper Lee must have considered Halloween an appropriate night for the evil act perpetrated by Bob Ewell, and the holiday is perfect for the actions performed by the ghoul-turned-hero--the "malevolent phantom," "Boo" Radley. Lee deliberately creates a "scary" setting for Jem and Scout, who must walk to and from the school pageant by themselves on a moonless night, and the addition of it being Halloween--an evening universally known for its evil connotations--is the perfect complement for the events that follow the children's return home. As for Lee's decision for Bob to seek revenge upon Atticus by harming his children, it is an event foreshadowed much earlier when Atticus wonders aloud
"What on earth could Ewell do to me, sister?" (Chapter 23)
and Aunt Alexandra answers "Something furtive." Lee creates a surprise ending by employing Boo as the hero, and it helps to tie together the two main plots of the story (the children's fascination about Boo, and the trial of Tom Robinson) when Boo and Tom's accuser meet on the dark trail from the school. Good finally triumphs over evil: Bob gets his just dessert, and Scout's fantasy comes true when she finally gets to meet Boo, who is transformed from the scary, unseen neighbor into the saviour of the children.