Siobhan questions Christopher at school about the bruise on his face, but when Christopher says he is not afraid to go home, she drops the matter. Christopher goes home and searches in the trash can for his book, but it is not there. He thinks Father may have hidden it in the house, so he searches for it. In Father’s bedroom, he finds an old cardboard box, and in it his book. Under the book, he finds many unopened envelopes that are addressed to him. From the handwriting he guesses they may be from his mother. When he hears his father returning he takes just one envelope and goes to his own room, where he hides the envelope under the mattress. Later, he opens the letter and reads it.
The letter turns out to be from his mother, from an address in London. She says she has a new job working as a secretary in a factory. She says she loves him and would love to receive a letter from him. Christopher is puzzled because his mom has never had a job like she describes, she has never lived in London, and she had never before written him a letter. He looks at the postmark and sees it was written eighteen months after his mother died. He regards this as another mystery that he has to solve and decides to look at the other letters when he gets the opportunity.
Christopher discusses two different mysteries, one relating to a ghost that his uncle claimed to have seen in a shoe shop, and the other relating to the frog population in a pond at Christopher’s school. For the former, Christopher expects that science will eventually be able to explain the phenomenon of ghosts, and for the latter, Christopher offers a mathematical explanation for how such things work.
Six days later, Christopher gets the opportunity to look at all of the forty-three letters in the box. In the first one he reads, his mother tells him the mundane things she has been doing and then remembers a happy time they had together at Christmas two years ago. In another letter, she says that she was not a very good mother. She recalls an incident in a crowded store when Christopher got frightened and became difficult to deal with. Later, she and her husband had an argument and she hit him. They had many arguments, and eventually she started seeing Roger (Mr. Shears), who wanted her to leave her husband and son and live with him. Initially she said no, but then things changed after she and Christopher had a serious argument in which Christopher threw a chopping board at her and broke some of her toes. For a while, as she recovered, Christopher’s father looked after him, and his mom noticed that Christopher seemed calmer with his father than he was with her. That made her think they would be better off if she wasn’t living in the house. So she and Roger made plans to live together in London. She planned to say goodbye to Christopher but Christopher’s father would not let her back in the house.
A third letter tells Christopher about a new job she has as a secretary in a chartered surveyors’ office. A fourth letter tells of a trip to the dentist.
Christopher feels giddy as he tries to process all the information, having just found out that his mother, whom he thought was dead, is alive after all. He realizes that his father lied to him. He lies down on the bed feeling unwell.
Some time elapses. When Christopher awakes, he does not know what happened. He notices vomit on the bed. It is now evening and his father comes into the room. He sees the letters and realizes what has happened. He says he is sorry, but he did it for Christopher’s own good. He didn’t know how to explain what had happened. Then he says he will run a hot bath for Christopher and then clean up the bed.
Christopher gives a long explanation of why people’s minds are like computers, and also repeats his often stated belief that there is no puzzle that cannot be solved if the right tools are applied to it. To those who believe that they are not like computers because they have feelings, Christopher has this response: “But feelings are just having a picture on the screen in your head of what is going to happen tomorrow or next year, or what might have happened instead of what did happen, and if it is a happy picture they smile and if it is a sad picture they cry.”
Analysis, Chapters 149-163
These four chapters follow the established pattern of plot development alternating with explanations of Christopher’s faith in, and knowledge of, science, computers, and mathematics. The difference from previous chapters is that the plot is now starting to move more swiftly, and the chapters that advance the plot are longer. It is hard for Christopher to process the fact that his father has lied to him consistently for years (as it would be for any boy of Christopher’s age, whether autistic or not). He is also beginning, bit by bit, to uncover the turbulent family dynamics that he will eventually learn have an important bearing on the mystery he is trying to solve.