Final answer:
Chuck catches Stephen in his lie when Amy confesses about lying and not knowing Stephen. He becomes angry and disbelieving and questions her association with people of color. Amy then comes up with a plan to keep Chuck occupied while Stephen escapes.
Step-by-step explanation:
In the story, Chuck catches Stephen in his lie when Amy confesses that she lied about Stephen being her brother and that she had never seen him before. Chuck is initially relieved by this revelation but then becomes angry and disbelieving, stating that he knows a white girl when he sees one. This prompts Amy to come up with a plan to keep Chuck occupied and give Stephen time to escape from town.