Christopher Boone, a mathematically gifted teenager with autism, discovers his neighbor's dog, Wellington, has been murdered and decides to investigate the crime himself. Christopher's investigation into Wellington's death leads him to uncover a series of profound secrets about his own family, forcing him to confront his deepest fears and navigate a world that often misunderstands him. He must overcome his aversion to physical contact and social interaction to piece together the truth, all while adhering to his strict logical framework and avoiding situations that cause him distress. The narrative is presented through Christopher's unique, often literal, first-person perspective, revealing his internal thought processes and his struggle to comprehend the complexities of human behavior and emotion.

The novel is widely praised for its unique narrative voice and its sensitive portrayal of a protagonist with autism. Critics often highlight the book's ability to blend a compelling mystery with a deeply personal story of self-discovery and family dynamics. Readers frequently connect with Christopher's distinct perspective, finding both humor and poignancy in his literal interpretations and his quest for truth. The book is celebrated for its intelligence, emotional depth, and its success in making complex themes accessible and engaging.