Back at school, Christopher shows Siobhan what he’s written so far and tells her he has to stop his detective work, so the book can’t have a real ending. He doesn’t like the idea that the murderer is still on the loose. He tells Siobhan about Mr. and Mrs. Shears, and she guesses that Ed might not like Mr. Shears because he hurt Mrs. Shears by leaving. Christopher points out that his father doesn’t like Mrs. Shears anymore, either.
Christopher really does intend to keep his promise to his father, even though it means ruin for the work that he’s been enjoying. Siobhan continues to play her role as Christopher’s interpreter of the world of emotion that he can’t understand. However, her inability to satisfactorily explain Ed’s anger confirms the suspicion that there’s more to find out.
Christopher sees four yellow cars both of the next two days, so they’re “Black Days” and he keeps to himself more than ever. He presses his head into the library wall and groans, which makes him feel safe. On the third day, he keeps his eyes closed on the way to school so he can’t see more yellow cars.
Once again, Christopher demonstrates his investment in the rules that govern his private world. Even so, he’s willing to manipulate fortune and his own rules by closing his eyes so that he isn’t forced to have another “Black Day.” This implies that the luck of the cars is not an objective law, but contingent upon his actually being aware of the cars; thus, he partly makes his own Black Days.