How does Lee use light and darkness to create the tone at the beginning chapter 28?

The walk back is even darker than before, and near the school, Scout remembers that she left her shoes backstage. She is thinking of returning to get them, when Jem stops her because he hears a strange noise. Scout hears it too, but thinks maybe it's just Cecil again. They call out taunts to Cecil in order to get a response, but there is only silence. Jem thinks maybe Scout should take off her costume, but she doesn't have any clothes underneath, and can't get her dress on in the dark. They are almost home, near the dark shadow of the tree by the Radleys' house, and are trying to walk faster. It sounds like the person behind them is wearing thick cotton pants.