As early as 1962, it was reported that the sales of Agatha Christie's books had comfortably overtaken Shakespeare and made her the most widely read British author in the world, with only the Bible more widely translated. That same year her play, The Mousetrap, celebrated its tenth year in continuous production in London -- now a 47-year run Christie was a discreet, private person who avoided celebrity and disliked publicity, to the extent of staging...