The Curious Incident of the Dog in the Night-Time established Mark Haddon as a writer of adult fiction. It won the Whitbread Book of the Year prize, The Guardian Children’s Fiction Prize, and the Booktrust award for teenage fiction. The novel’s main appeal is the character of its narrator, fifteen-year-old Christopher Boone, whose counselor in his special-needs school has suggested that he write a book, and so he does. Although the words “autism” and “Asperger’s syndrome” are never mentioned in the novel, it soon becomes clear that Christopher has a high functioning form of autism. Because of the particular way his brain is wired, fiction is unappealing to him; he cannot tell lies or understand most made-up stories. As he tells his narrative, the list of his quirks grows ever larger. He cannot eat things colored yellow or brown. He cannot be touched. Seeing three red cars in a row on the way to school means that it will be a good day.

Christopher, however, is a very bright child. In mathematics, his abilities are far beyond his age. He is intensely observant of the world around him, even though its human inhabitants are mostly a mystery to him. He loves puzzles and is very good at them, so it is no surprise that he likes the Sherlock Holmes mysteries of Sir Arthur Conan Doyle; Holmes’s dispassionate analysis of clues is especially appealing to him. Thus he has decided to write a mystery to address his counselor’s assignment.

From the opening pages, Christopher’s special gifts, as well as his special limitations, are apparent. He numbers his chapters using only prime numbers (2, 3, 5, 7, 11, and so forth). He always knows the precise time, and he notices that one of his teachers wears brown shoes with approximately sixty small circular holes in them. When Christopher finds a dead poodle, he is sad; he likes dogs, whose moods are much less puzzling than human moods, and he resolves to discover its killer.

Christopher’s discovery of the dog leads to a skirmish with the dog’s owner, who calls the police. When the policeman asks too many questions too fast, Christopher employs his usual method of coping with overload—he lies down and begins groaning. When the policeman tries to force him to get up, he becomes frantic and hits the man because of his intolerance for being touched. When his father comes to get him out of jail, the two fan out their fingers and touch their hands together; this gesture, created by his father, means “I love you” and substitutes for the hug that Christopher cannot bear. Throughout the novel, Christopher’s father seems to be a man who is doing his best in a nearly impossible circumstance, raising his difficult son alone. However, here his father testily tells Christopher to give up the idea of investigating the poodle’s death.

Christopher does not stop the investigation, however. It is the subject of his book, and he begins interviewing some of the more approachable neighbors, but timidly, because he is fearful of strangers. When his father learns of the book, he throws it away, with the inevitable result that Christopher searches until he finds it in his father’s closet, along with a packet of letters his mother has written him every week since his father told him she died of a heart attack. Now he learns that she is alive, living in London with the husband of the neighbor who owned the dog. She confesses that she thinks Christopher is better off with his father, who has more patience than she did; nevertheless, she loves Christopher and is puzzled that he has never written her.

The letters occupy the exact center of the novel and form a turning point for what happens to Christopher, for when his father discovers him reading the letters, he tries to explain his terrible lie, talks about his liaison with the dog-owning neighbor after his wife’s departure, and finally confesses that he himself killed the dog in a bout of anger. Christopher is left with only one possible conclusion: His father is a dangerous man who may also try to kill him.

That conclusion leads Christopher to start his bold trip to London. He surmounts all the obstacles, although sometimes he does so awkwardly, hiding in a luggage compartment for most of the train trip, sitting terrified in the subway station for six hours, and risking his life among the subway rails to rescue his pet rat Toby. When at last he arrives at his mother’s apartment, he is met with the awkward fact that her partner is not at all glad to share the flat with someone whose needs are as complicated as Christopher’s. In the end, his mother moves back to Swindon with Christopher, although she does not return to his father. In the novel’s last chapters, it is clear that his father is willing to make a herculean effort to regain Christopher’s trust. He takes the first step by buying him a dog, to Christopher’s pleasure. Christopher passes his A-level mathematics exam with an “A,” adding to the novel’s hopeful conclusion.

Written by British author Mark Haddon and published in 2003, The Curious Incident of the Dog in the Night-Time is told from the point of view of Christopher John Francis Boone, a 15-year-old autistic boy. Christopher takes the reader through typical days in his life and explains, clearly and coherently, sometimes in an almost detached way, what it is like to be autistic. (Christopher has Asperger's syndrome, but that disorder is never specifically mentioned in the book.) He discusses his routines; his counting of cars (five red cars in a row on the way to school make it a Super Good Day, but five yellow cars in a row make it a Black Day during which he will Take No Risks); why people, facial expressions, and idioms confuse him; his inability to lie; and his standards and requirements for eating. Christopher also takes the reader into his mind when he has one of his "episodes"—when his brain gets so overloaded with stimuli that he can only rock back and forth and moan. The patterns, the counting (even, for example, the novel's chapters are ordered as prime numbers because Christopher likes them), the moaning, and the selective behavior all seem perfectly logical when explained by Christopher.

The novel's inciting incident occurs when Christopher finds his neighbor's dog, Wellington, speared by a garden fork in his neighbor's front yard. Christopher cannot comprehend how someone could do this, so he removes the garden fork from the dog and cuddles the dog's body. Christopher is questioned by the police when they arrive, and it is here that the reader learns of Christopher's dislike of people touching him: he assaults the police officer and is then taken home by his father, Ed. Christopher takes it upon himself to find Wellington's killer and, as he explains at the beginning of the novel, to write a book about it with the help of his schoolteacher, Siobhan. To solve the mystery, Christopher uses different techniques he has discovered from various detective books (including his favorite, Sherlock Holmes), like making a map of the neighborhood and "trying a different tactic." Christopher's father insists that Christopher drop the investigation and stay away from Mrs. Eileen Shears, the owner of Wellington.

Christopher carefully makes his way around his father's rules, going to neighbors' houses and asking questions regarding the dog's murder. His first stop is Mrs. Shears, who does not want to talk to Christopher. His prime suspect becomes Mr. Roger Shears, Mrs. Shears's ex-husband. He begins to ask the neighbors about Mr. Shears and is informed by one, Mrs. Alexander, that his mother and Mr. Shears were having an affair before she died. Christopher's father finds Christopher's notebook about the case, and hits Christopher, telling him to stop with the investigation. Christopher's father then throws away the notebook, and while Christopher is searching for it, he finds letters from his mother, Judy, that had been hidden from him by his father. Judy moved away two years earlier, but Christopher had been told by his father that she had died in the hospital of a heart attack. Christopher's father finds him reading the letters, and his father confesses to the murder of Wellington. His father explains that Mrs. Shears had been wonderfully nice after Christopher's mother had left, and he thought they could have moved in together; however, he says she loved her dog more than anything else. After one particularly bad fight between Mrs. Shears and Christopher's father, she kicked him out of her house and he then killed Wellington, calling the dog "schizophrenic after its operation." His father blames the killing on negative emotions he had suppressed for two years.

Not being able to live with a murderer, Christopher decides to travel by train to find his mother in London. He sneaks out of the house with his backpack, his Swiss Army knife, and a few provisions. He spends the night in the garden, explains his situation to Mrs. Alexander, takes his rat Toby and his father's PIN number, and then travels to London. Using logic, straight-forward question asking, and the address from his mother's letters, Christopher finds himself—cold, alone, and covered in dirt—at his mother's apartment after an arduous journey. His mother is delighted to see Christopher and pained to know his father had been lying to him. Christopher's father eventually comes looking for him, and a fight ensues between Christopher's father, his mother, and Roger about what to do with Christopher and where he should live. He eventually ends up with his mother, who leaves Roger, and the adjustment period is difficult for everyone, primarily because the most important thing on Christopher's mind is taking his A-level examination in mathematics.

Ed eventually tries to mend his relationship with Christopher by buying his son a puppy. Meanwhile, Christopher continues to go to school and plans to become a scientist, which is supported by his drawings, diagrams, and lists presented throughout the book.