The Guardian Bookshop makes over 180,000 books available with up to 40% discount, as well as highlighting some of our favourite publications in each genre.
Find out more.
At the end of Agatha Christie's classic detective novel, The Murder of Roger Ackroyd, Hercule Poirot declares with a customary late flourish that the murderer is none other than the book's narrator. But the narrator is, by definition, suspect. So who can we believe?