When Christopher gets home, he finds his father socializing with Rhodri, his employee. His father quizzes him about where he has been, and Rhodri asks him to multiply 251 by 864. Christopher gets the answer very quickly, but Rhodri has no idea whether he is right or not, and just laughs. Christopher does not like this and goes out into the garden. Siobhan has told him that a book should have descriptions of things in it, but the only thing Christopher finds interesting outside are the clouds, which he describes in detail. He also tries to listen to the sounds in the garden.
Christopher notes that his favorite book is The Hound of the Baskervilles, a Sherlock Holmes story by Sir Arthur Conan Doyle. He summarizes the story’s plot and explains that he likes the book because it is a detective story, which means it includes clues and red herrings, and he describes some of these. He also likes Holmes, whom he thinks is very intelligent, and he also thinks that Holmes’s intelligence resembles his own.
Siobhan reads Christopher’s book during morning break at school, and she asks him if he is sad that his mother and Mr. Shears had an affair. He says he is not, because Mother is dead and Mr. Shears no longer lives in the neighborhood.
Christopher explains why his memory is so good. He says his memory is like a soundtrack of a film and he can rewind it to any point in his life he chooses. He can remember things very exactly, and he describes a time he spent on the beach in Cornwall with his mother when he was nine. But he cannot remember anything before he was four.
He uses his memory to find out how to respond in difficult situations. He does a memory search to see if he has ever encountered such a situation before. If he has, he can remember what he should do. He can only remember, through the pictures in his head, things that have really happened. He cannot form pictures in his head, though, of things that did not happen, such as imagining that he is living in a different place.
Analysis, Chapters 103-113
The now familiar structure of the book is very apparent in these four chapters, since they alternate plot development and internal reflection on the part of Christopher.
After chapter 103 moves the plot forward, the following chapter, 107, is another digression, which explains more of Christopher’s interests and his way of being in the world. This chapter, about Christopher’s love of Conan Doyle’s Sherlock Holmes stories, does have the advantage of explaining how such a disadvantaged boy (in terms of normal development) could plausibly be presented as writing a murder mystery. If he is presented as being interested in detective novels, that particular problem is solved. Also, Sherlock Holmes’s ability to notice things that others fail to see—often perfectly ordinary or obvious things—and his ability to focus entirely on the matter in hand, are qualities that Christopher has in abundance. By adding this kind of detail, the author, Mark Haddon, makes his story more believable and his character more convincing.
After these two chapters, the following two show the same pattern, of plot development followed by more introspection and explanation by Christopher of Christopher (in this case, how his memory works like a film).