Fifiteen-year-old Christopher has an extraordinary brain: He is exceptional at mathematics but ill-equipped to interpret everyday life. He has never ventured alone beyond the end of his road; he detests being touched, and he distrusts strangers. Now it is seven minutes after midnight, and Christopher stands besides his neighbor's dead dog, Wellington, who has been speared with a garden fork. Finding himself under suspicion, Christopher is determined to solve the mystery of who murdered Wellington, and he carefully records each fact of the crime. But his detective work, forbidden by his father, takes him on a thrilling journey that upturns his world.