After a bath, Father dries Christopher off and puts him in bed. Father apologizes for lying about Mother and keeping the letters from Christopher. He doesn’t want any more lies between them, so he confesses to killing Wellington. He explains how upset he was when Mother left him. Mrs. Shears helped him to get through it, but when he recently had an argument with Mrs. Shears, Mrs. Shears kicked him out of her house, and Wellington attacked him in the yard. Father killed Wellington with the garden fork. Christopher screams in terror at the news, and pushes Father off the bed. Father retreats downstairs, begging Christopher to go to sleep so that they can talk about the situation in the morning. Christopher decides he can’t trust Father. Because Father murdered Wellington, Christopher reasons, Father could also murder him. Christopher waits until 1:20 a.m., takes out his Swiss Army knife, and walks quietly downstairs. In the living room, Father sleeps on the sofa. Christopher goes into the kitchen, takes his special food box, and steps out into the garden. He hides behind the garden shed and eats two clementines and a Milkybar, then wonders what to do next.
From the space behind the shed, Christopher can see the constellation Orion. He says people call it Orion because it looks like a hunter with a club, but he says the stars in the constellation can be joined to make any number of shapes, such as a dinosaur. At any rate, he says, Orion is not a hunter: it is a series of 21 stars billions of miles away.
Christopher sleeps in the garden that night. In the morning, he hides as he hears Father come outside looking for him. After Father leaves, Christopher decides he should live with Mrs. Shears, but when he knocks on her door she doesn’t answer. He goes through the reasons he can’t live with Siobhan, Uncle Terry, or Mrs. Alexander, then decides to go to London to find Mother. The prospect frightens him because he has never been anywhere on his own before, but the idea of returning to Father’s house, or hiding in the garden every night, is far worse.
Christopher notices the circular lid of an old metal pan leaning against the side of Mrs. Shears’s house. The pan looks like the surface of a planet, with rust forming continents and islands. The image reminds him of his dream to become an astronaut, and he feels disappointed at how impossible it now seems. Going to London, which is only a hundred miles away, scares him. He would have to travel thousands of miles away as an astronaut.
Christopher goes to Mrs. Alexander’s house and tells her he needs someone to watch Toby while he goes to London. He says he is going to live with Mother because Father lied to him about Mother’s death and killed Wellington. Mrs. Alexander tries to get him to come inside, but when she says she’s going to phone Father, Christopher panics and runs back home. Christopher grabs his schoolbag and fills it with food, a change of clothes, and some math books. He feels afraid when he spots Father’s mobile phone and wallet next to the kitchen sink, but remembering that Father’s van was not outside, he realizes Father forgot the items. Christopher takes Father’s bankcard, the pin to which Father told Christopher in case Christopher ever needed it.
Christopher puts Toby in his pocket and walks to school, intending to ask Siobhan the location of the train station. The further Christopher gets from home the less frightened he feels of Father but the more frightened he feels of being alone. He describes his fear as mathematically constant.
Christopher sees Father’s van in the school parking lot and vomits at the sight. To calm himself, he does cubes of numbers and counts fifty breaths. He decides to ask a stranger for directions to the train station instead. The woman he asks points him in the direction of the station and tells him to follow a bus that is passing. Christopher runs after the bus but can’t keep up. He walks at the edge of the road for a while until he spots a railway sign. He starts to walk towards it, but in his confusion he loses sight of the sign. He comes up with a plan. He knows that if something is nearby you can find it by moving in a clockwise spiral, taking every right turn until you come back to a road you have already walked on, then expanding your spiral to streets you haven’t checked. In this way, he finds the train station.
When Father admits to killing Wellington, the novel finally resolves the initial mystery that set the plot in motion and conclusively ties Wellington’s murder to the tangle of relationships Christopher has gradually uncovered between his parents and Mr. and Mrs. Shears. Over the course of the novel, Christopher’s inquiry into Wellington’s death has consistently turned up more secret information about Mother and Father than it has about Wellington, turning the investigation of Wellington’s murder into a broader symbol of Christopher’s search for the truth about his parents. Here, the two investigations finally converge, as Christopher’s discovery of Mother’s letters also prompts Father to admit to killing Wellington. By this point, the mystery of Wellington’s death, which provided the driving force for the early chapters of the novel, has become the less important puzzle, and the history of secret relationships between Mother and Mr. Shears and between Father and Mrs. Shears has taken over.
Christopher’s observations on the constellation Orion appear to comment indirectly on the way Christopher now views Father, since Christopher now knows that Father murdered Wellington. Christopher thinks about Orion as he hides outside in the garden, just after Father reveals himself to be Wellington’s killer, and both this timing and Christopher’s thoughts themselves suggest that Christopher draws a parallel between Father and Orion. Like Orion, which appears to be a hunter but is in truth a series of explosions that exist billions of miles away, Father appears to be one thing, specifically a loving caretaker to Christopher, and in fact turns out to be a liar and a murderer. Christopher’s observation that the stars in Orion look as much like any number of things, such as a dinosaur, as they do a hunter also acts as a comment on subjectivity. While one person may see a hunter in the stars that make up Orion, another person—to use an example Christopher gives—could see a teapot. Father, meanwhile, may appear to be a kind man to some, but a person with a different perspective, such as Mrs. Shears or Christopher, can view him quite differently.
The extreme fear Christopher feels toward his father reiterates what the reader has already seen in terms of Christopher’s view of social relationships. Christopher feels most comfortable with people when they act predictably. Early in the novel, he says he even feels comfortable being arrested after he hits the officer because arresting someone represents a predictable behavior for a police officer. Christopher’s father, on the other hand, has not acted predictably by killing Wellington, and as a result, Father’s confession actually frightened Christopher more than it reassured him, even though Father told Christopher about Wellington since he didn’t want any more lies between them. We’ve also seen that honesty plays a significant role in Christopher’s feelings toward a a person, evident from Christopher’s description of love. Since Father lied to Christopher about Mother, then revealed that he acted violently and stabbed Wellington, Christopher doesn’t feel safe with Father. He decides to run away, setting in motion the novel’s final act.