Father has prepared supper when Christopher comes home; Christopher's plate is laid out so the different foods were not touching because if they touched he could not eat them. Father asks where Christopher has been and he responds that he's been out, which is a white lie. Christopher explains that a white lie isn't a lie at all, but not telling the whole truth. Father says that he received a phone call from Mrs. Shears and reminds Christopher to keep his nose out of other people's business. Christopher tells Father that Mr. Shears is the Prime Suspect, but this only angers Father further. He bangs the table and knocks some of the food together, meaning Christopher couldn't eat it anymore. Father does not want the man's name mentioned in the house because he is evil; Christopher asks if that means he might have killed Wellington, which only frustrates Father further. Christopher adds that he knows he was told not to get involved but Mrs. Shears is a friend; Father says she's not a friend anymore. Father repeats his orders to Christopher: to not ask Mrs. Shears about who killed the dog; to not ask anyone about who killed the dog; to not trespass in other people's gardens; and to stop the detective game. Father makes Christopher promise this, and he does.
Notes - More clues about the second mystery are provided in Father's reaction to Mr. Shears. Ironically, while Father told a lie about what happened to Mother, according to Christopher's view of the world he only told a white lie about Wellington since he never denied killing the dog because he was never asked.
Christopher believes he will make a good astronaut because he is intelligent and likes being in tiny spaces on his own. He wouldn't be homesick because he'll be surrounded by things he likes. He would like to take Toby with him, perhaps as part of an experiment, but would go even if Toby couldn't because it would be a Dream Come True.
Notes - The depths of Christopher's isolation are revealed in his reasons for wanting to be an astronaut. What many would consider a drawback - being alone in a tiny space - is one of the aspects that most appeals to him.
The next day Christopher tells Siobhan that Father wants him to stop detecting and so the book was finished. Siobhan likes the book and says Christopher should be proud of himself, but he insists that it isn't a proper book since there is no proper ending because the murderer of Wellington was still At Large. Siobhan compares this to real life, such as Jack the Ripper, but this does not appease Christopher. He mentions how Father did not like hearing Mr. Shears' name and thinks he may be the killer and Siobhan suggests that he may just not like Mr. Shears very much. She adds that Mrs. Shears is a friend and so Mr. Shears' treatment of her may be why Christopher's father doesn't like him. However, Christopher points out that Father claims Mrs. Shears is no longer a friend. Siobhan doesn't know what else to say. The next two days Christopher sees four yellow cars in a row, meaning they were Black Days and so he keeps to himself. On the third day he closes his eyes all the way to school because he's allowed to do that after two Black Days in a row.
Notes - More clues abound in the hidden second mystery, but again the misdirection continues to draw the reader's attention to Wellington. Note how Christopher gives himself a way out of facing too many Black Days in a row, which shows that he can make accommodations to make his life more tolerable.
Five days later Christopher sees five red cars in a row, which is a Super Good Day. He goes to buy candy at the local shop and meets Mrs. Alexander again, who asks why he ran off the other day. He explains that he was afraid she would call the police but she doesn't understand why he'd think that. As Mrs. Alexander makes her purchases, Christopher goes outside and pets Mrs. Alexander's dachshund. When Mrs. Alexander soon joins him and says the dog's name is Ivor. At first, Christopher doesn't want to chat with Mrs. Alexander but decides that since it's a Super Good Day, something special should happen but hasn't yet. He thinks he can find out from her something about Wellington or Mrs. Shears without asking her, which would mean he doesn't break his promise to Father. He tells Mrs. Alexander about taking A-level maths and he watches while she cleans up after Ivor's poo.
He thinks of the different orders given by his father and decides to take a risk since today is a Super Good Day. So he asks Mrs. Alexander if she knows Mr. Shears. She says she knows him only in passing and suspects he's asking in relation to Wellington. She then believes it best not to talk about these things because Christopher's father is right and he shouldn't be asking questions on this topic. Christopher asks if Mr. Shears killed his Mother, which Mrs. Alexander denies. He asks if Mr. Shears caused Mother enough stress to die of a heart attack and Mrs. Alexander is surprised to hear Christopher's Mother had been in the hospital and died. Mrs. Alexander realizes Christopher doesn't know something she does and decides to tell him as long as he promises not to tell his father she did so. She knows that if she doesn't answer, Christopher will keep pushing and it will upset his father. Christopher makes his promise and Mrs. Alexander tells him that before she died, Christopher's mother and Mr. Shears were having an affair. She apologizes and says she didn't mean to upset Christopher, but he needed that answer and didn't want his father to relive bad memories. Christopher asks if this is why Mr. Shears left Mrs. Shears and Mrs. Alexander says she expects so. Christopher goes home, but not before Mrs. Alexander reminds him of the promise he made her.
Notes - Using language to his advantage, Christopher follows the exact instructions of his father while still going against his overall wish - that is, he observed the letter of the law but not the spirit of it. Mrs. Alexander's surprise about Christopher's mother's hospitalization and death are a clue as to her real whereabouts. Christopher's views on human relations is very specific, so he describes the relationship between his mother and Mr. Shears not under the euphemism of an affair or the even subtler "very, very good friends" (as Mrs. Alexander says), but that "they were doing sex". This cuts to the heart of the matter but does not trouble Christopher because it is the truth.