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...