Christopher tells us that he wrote some more of his book the night before and that he showed it to Siobhan the next day. She asked him if he was sad about the conversation he'd had with Mrs Alexander and that he could talk to her about it if he ever did feel sad. Christopher says that, since his mother is dead and Mr Shears isn't around, it would be stupid to be sad about something that doesn't exist.
Christopher explains how his memory works. He says it is like a DVD that you can rewind to any point and replay the situation exactly - so long as it was after he was four years old, he clarifies, because that was when he started looking at things properly. He tells us about a scene with him and his mother in Cornwall when he was nine in 1992. To recognize someone he does not know he does a Search through his memories to see if he's seen their walk or glasses or hair before. He says he has pictures in his head of things that happened but can't understand the pictures people make up in their heads of things that haven't happened.
Christopher gets home before his father and puts his things on the kitchen table (including his book) and sits in the living room to watch a Blue Planet video. When his father comes home at 5.48pm he is in a good mood but goes to the kitchen and stays there until 5.54pm, when he reemerges with Christopher's book in hand. He is quiet to start, so Christopher doesn't know that he's angry, but he soon starts shouting about the conversation Christopher had with Mrs Alexander. He grabs Christopher (which he has never done before), who hits him back. At this point Christopher's memories stop and he only remembers sitting against the wall with blood on his right hand. His father leaves for the garden, still with the book in his hand, and puts it in the bin.
Christopher states some reasons why he hates the colors yellow and brown. He recalls that Mrs Forbes said it was silly to hate yellow and brown but that Siobhan had said that she shouldn't say things like that because everyone had favorite colors. Christopher does say he thinks it is silly in a way but says that in life you have to make decisions and if you didn't you would 'never do anything because you would spend all your time choosing between things you could do.'
The next day Christopher's father says he's sorry for hitting him and says he will take Christopher to Twycross Zoo to show that he really was sorry. At the cafe at lunch, Christopher's father apologizes again and tells Christopher how much he loves him. Then Christopher draws a map of the zoo from memory.
Christopher tells the story of The Case of the Cottingley Fairies where, in 1917, two cousins - one nine and one sixteen - took photographs of the fairies they used to play with. People believed the photographs for years but Christopher says it is stupid and that the cousins admitted it was a fake in 1981.
After school on Monday - when Siobhan had questioned Christopher about his bruised face and asked if he was scared to go home - Christopher went into the bin in the garden to look for his book. He missed it and liked having a project. He couldn't find it there, so he looked around the house. He looked in his father's room, even though he had said that Christopher shouldn't mess with anything in there. Christopher determines to move everything back where it was so he will never know. He finds his book in a shirt box in the cupboard and doesn't know what to do because if he moves it his father will know he had been messing around.
Christopher hears his father come home and makes a quick decision - he will leave the book there and copy information out of it when necessary when his father is not home. Just then he notices a letter addressed to him. He takes the letter and quietly leaves his father's room, hides the letter under his mattress, and goes downstairs to have dinner with his father.
When he goes back up to his room he opens the letter. It is from his mother, writing from London. It is dated a year and a half after she died.
Christopher says that it must be a letter to another Christopher from his mother, and that he was in the middle of another mystery.
In this chapter Christopher explains that there are mysteries for which we have no answer, but science will one day explain all. Lightening was a mystery before they realized it was electricity, and one day ghosts will be explained too.
When Christopher describes his memory as a DVD player, we realize that he is embodied in the novel - we hold a copy of his mind, the DVD that it plays back. We can turn back the pages at whatever point to replay any scenes. Christopher grants us his power for replaying situations exactly, putting us in his shoes.
When Christopher and his father have a fight, his memory is significantly wiped out - that of course is when the book is thrown away. His connection with the outside world is momentarily halted and it seems no coincidence that this is precisely the time when the book is discovered by his father and thrown away. His connection with the outside world is through his book and they have almost become one and the same.
Christopher here is distinguishing between real and fake, in a novel primarily about deceit. Although Christopher understands very clearly that the fairies are a fake he has not yet uncovered the lies happening right before him. It also points to how convincing art can be - the photographs were thought of as real in the way that this novel is presented as non-fiction.
Christopher finds himself in a mini mystery when he is searching for his book and this mystery leads him to a truth long hidden: his mother is still alive and living in London. Suddenly we have found ourselves in a far more vital mystery than that of the dog - we want to look back and see what actually happened to his mother. Because Christopher has been lied to and we see the world from his eyes, we feel equally betrayed.
When Christopher first finds his mother's letters to him, he cannot believe that they are what they appear to be - so much so that he believes he has intercepted a letter meant for a different Christopher. When faced with contradictory facts, Christopher's logical brain presents the simplest solution to arrange them - a lie is not an option, because he is incapable of conceiving of willful deceit.