Christopher John Francis Boone is a 15-year-old boy living in Swindon, England, with his widowed father, Ed. Christopher's mother, Judy, is believed to have died two years earlier. When Christopher discovers his neighbour Mrs. Shears's dog, Wellington, has been killed, be begins a detective investigation to prove his innocence after being accused. His journey uncovers family secrets, emotional truths, and challenges that test him deeply.