Inspired by his Good Day, Christopher draws a map of his neighborhood and sets out to question the people on his block about the murder. He does not like talking to strangers, so he clutches his Swiss Army knife tight inside his pocket as he approaches Mr. Thompson’s house. Mr. Thompson claims to have been away on the night of the murder. The resident at Number 44 does not have any information. Christopher next tries number forty-three, but the occupant jokes about policemen getting younger and younger, and Christopher, who hates being laughed at, walks away. He skips Number 38 because he fears the people who live there. At Number 39, Mrs. Alexander, an elderly neighbor, works in her front garden. She has nothing to add regarding Wellington’s murder but invites Christopher in for tea. He refuses to go inside, so Mrs. Alexander decides to bring biscuits out for him. Christopher, however, worries she might be calling the police and walks away.
Christopher has an insight about who might have killed Wellington. He figures there are three reasons someone might kill a dog: because they hate the dog; because they are crazy; or because they want to upset the owner. Christopher cannot think of anyone who hated Wellington and does not know anyone who is crazy. He does know that most murderers know their victim and that the only person who would want to upset Mrs. Shears is Mr. Shears. Mr. Shears left about two years ago and didn’t come back. When Mother died, Mrs. Shears would come over and cook for Christopher and his father because she felt lonely, too. Sometimes she even stayed overnight. Christopher doesn’t know why Mr. Shears left Mrs. Shears, but if Mr. Shears didn’t want to live in the same house as Mrs. Shears anymore he probably hates her. He might have decided to kill Wellington to make her sad. Christopher decides to find out more about Mr. Shears.
Christopher considers all of the other children at his school stupid. He knows he should refer to them as “special needs” but finds that term silly because everyone has special needs. Siobhan needs very thick glasses in order to see, and Mrs. Peters has to wear a beige-colored hearing aid in order to hear. Christopher plans to prove that he is not stupid like his peers by scoring an A grade on his A-level math test, which no one at his school has done before. After the A-level math test he will an even more advanced math test and an advanced physics test, and use his scores to attend college in another town.
Christopher describes the arguments that his mother and father used to have as so bad that he thought they might get divorced. Their fighting, he says, had to do with the stress that resulted from taking care of him and dealing with his behavioral problems. He recalls that sometimes his behavioral problems would make his mother and father angry at each other. His mother used to say Christopher would lead her to an early grave. He writes that many of his problems have gone now, because he has grown up and can make decisions for himself.
In the course of Christopher’s investigation, we see both Christopher’s strengths and the disadvantages he faces. Although Christopher gets little useful information out of his neighbors, his analytical skills provide him with a key insight about who killed Wellington. He concludes logically that the murderer most likely knew Wellington beforehand. At the same time, however, Christopher apparently remains blind to the nature of Father’s relationship with Mrs. Shears. He recalls that Mr. Shears moved out at roughly the same time that Mother died, so Mrs. Shears would often cook dinner for Christopher and Father because she felt lonely, too. Christopher notes that Mrs. Shears would sometimes stay the night, suggesting she and Father had a sexual relationship. Christopher doesn’t recognize this detail, presumably because he doesn’t stop to imagine what motivation Mrs. Shears might have for sleeping over when her own bed is just next door. The significance of this relationship remains unclear, but Christopher doesn’t even realize it may provide a lead worth looking into.
Although Christopher never displays any guilt over his mother’s death, his writing suggests that he may feel responsible for her death (though whether he actually does or not remains uncertain). Notably, Christopher says that the problems caused by his behavioral issues led Mother and Father to fight at times, and he is aware that his actions caused his parents a great deal of stress. Christopher then recalls his mother telling him he would drive her into an early grave. He mentions this detail shortly after talking about how she died surprisingly young. Christopher, however, never stops to reflect on this detail. He avoids his own emotional reaction to this comment, perhaps because he had no reaction or because he feels uncomfortable recalling it, and instead picks up with the events that occurred after he went home from questioning his neighbors. The reader can only guess whether Christopher connects his behavioral problems to Mother’s comment and ultimately to Mother’s death.