Though Mark Haddon is an award-winning scriptwriter for television and radio shows, and though he is a painter, a poet, and has written and illustrated many books for children, The Curious Incident of the Dog in the Night-time is his first novel. The main character is Christopher John Francis Boone, a fifteen-year-old boy with autism. The fact that, as a young man, the author worked extensively with autistic individuals is immediately evident by the way Christopher is created, developed and personified in the story.

What starts out as a simple mystery for Christopher quickly spirals into something totally beyond chaotic -- especially to a child with autism. Christopher is a special boy with demonstrated and extraordinary math skills, but when he finds his neighbor's dog dead all he can think to do his hold the animal in his arms. Mrs. Shears sees the boy holding her dead dog and calls the police. Unable to clearly explain what he is doing with the carcass, the police decide to take the boy to the station. The officer makes the mistake of touching Christopher; hating to be touched, Christopher belts the cop.

Christopher's father may be able to clear up things with the police, but he struggles to help his son to forget about investigating the murder of the neighbor's dog. And so Christopher chronicles his investigations in a journal and shares the entries with his teacher and friend, Siobhan. However, many of the truths uncovered are secrets that people prefer to have kept buried away. The first problem: Christopher is mentally unable to stop until he has the all of the answers. The second problem: The answers Christopher learns are enough to risk upsetting the world as he knows it.

Though the book is oftentimes light and humorous, Christopher says it best when he starts chapter 13 (the chapters are all prime numbers):

This will not be a funny book. I cannot tell jokes because I do not understand them. Here is a joke, as an example. It is one of father's. His face was drawn but the curtains were real. I know why this is meant to be funny. I asked. It is because drawn has three meanings, and they are (1) drawn with a pencil, (2) exhausted, and (3) pulled across a window, and meaning 1 refers to both the face and the curtains, meaning 2 refers only to the face and meaning 3 refers only to the curtains…"