When Christopher gets home, Father has made supper and sits at the table in the kitchen. Father has carefully arranged Christopher’s food on his plate so that no food item touches another. Father asks Christopher where he has been. Christopher responds with a white lie—that he has been out—because it is only a partial retelling of the truth, and not made up. Father notes that Mrs. Shears has already called to report that he had been poking around her garden. Christopher explains that he thinks Mr. Shears killed Wellington. At the mention of Mr. Shears, Father bangs the table in anger. He forbids Christopher from ever mentioning Mr. Shears’s name again and orders him to stop asking questions about who killed Wellington. Christopher sits in silence for a moment. He promises Father that he will do as Father says.
Christopher wants to be an astronaut. He explains the many ways the job fits him: he is intelligent, he understands how machines work, and he doesn’t mind small spaces, so long as he doesn’t share them with anyone. Besides, no yellow or brown things exist on spaceships, and the stars would surround him. It would be a dream come true.
At school the next day, Christopher shows Siobhan his “finished” book. Now that he has promised Father not to continue the case he won’t be able to write it anymore. Siobhan says it does not matter, that he has written a good book and should be proud to have written it. But to Christopher the book lacks an ending. He has not found the murderer and the idea that the person who killed Wellington could be living somewhere nearby, waiting for him when he goes for a walk at night, bothers him. After all, murderers tend to know their victims.
Christopher tells Siobhan that Father told him never to mention Mr. Shears’s name in the house again. Siobhan points out that Mrs. Shears is a friend of Christopher and Father, so perhaps Father doesn’t like Mr. Shears because he left Mrs. Shears, which would constitute doing something bad to a friend. Christopher points out that Father said Mrs. Shears isn’t a friend anymore either.
The next day Christopher sees four yellow cars in a row on his way to school, making it a Black Day. He doesn’t eat anything at lunch and reads by himself in a corner during class. The next day he sees four yellow cars again. On the third day he keeps his eyes closed on the ride to school to avoid another Black Day.
Chapter 79 hints at some uncomfortable history between Christopher’s father and Mr. Shears that the reader has not learned about. Most notably, we see Christopher’s father become angry to the point of a physical outburst when Christopher brings up Mr. Shears at the kitchen table. Although Father seems to be exploding at Christopher mostly as a result of the other pressures in his life, the anger arises specifically at the mention of Mr. Shears. Father then forbids Christopher from speaking of Mr. Shears again and calls Mr. Shears “evil.” This strong emotional reaction to Mr. Shears suggests that something occurred in the past which Christopher—and thus the reader—does not know about at this point. The fact that Mr. Shears is currently Christopher’s prime suspect in Wellington’s murder suggests his character may play a more significant role later in the novel. When Father forbids Christopher from inquiring anymore about Wellington, he creates a new conflict for Christopher. Christopher must decide between obeying his father and doing what he wants.