Christopher, fifteen years old, stands beside Mrs Shears’s dead dog. It has been speared with a garden fork, it is seven minutes after midnight, and Christopher is under suspicion. He records each fact in the book he is writing to solve the mystery of who murdered Wellington. He has an extraordinary brain and is exceptional at maths, but he is 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. But Christopher’s detective work, forbidden by his father, takes him on a frightening journey that turns his world upside-down.