The novel is narrated in the first-person by Christopher John Francis Boone, a year-old boy who is described as "a mathematician with some behavioural difficulties" living in Swindon , Wiltshire. Although Christopher's condition is not stated, the book's blurb refers to Asperger's syndrome. The book is not specifically about any specific disorder", and that he, Haddon, is not an expert on the autism spectrum or Asperger's syndrome. The book uses prime numbers to number the chapters, rather than the conventional successive numbers.
Originally written in English, it has been translated into 36 additional languages. Christopher's mother, Judy, died from a heart attack two years prior to the events of the story. One night, Christopher discovers that his neighbour Mrs. Shears's dog, Wellington, has been fatally speared with a garden fork.
As Christopher mourns over Wellington's body, Mrs. Shears calls the police. When a policeman grabs Christopher's arm, Christopher panics and hits him, so he is arrested for assaulting a police officer, though he is quickly released with a police caution. He decides to investigate the dog's death, despite his father's objections, chronicling any information he receives in a book. During his investigation, he meets the elderly Mrs. Alexander, who informs Christopher that his mother had an affair with Mr.
Ed discovers the book and confiscates it. While searching his father's room for the book, Christopher finds letters from his mother dated after her supposed death, and eventually realises that she is still alive and living in London with Mr. He becomes distressed and enters a catatonic state. Realizing that Christopher has discovered the letters, Ed admits to lying about Judy's death. Ed also confesses that he had killed Wellington in anger after an argument with Mrs.
Christopher decides to run away and live with his mother. After a long, event-filled journey, evading policemen and feeling ill from the trains and crowds around him, he finally finds his way to the home of his mother and Mr.
