A fascinating exploration of the contents of Agatha Christie's 73 recently discovered notebooks, including illustrations, deleted extracts, and two unpublished Poirot stories. When Agatha Christie died in 1976, aged 85, she had become the world's most popular author. With sales of more than two billion copies worldwide in more than 100 countries, she had achieved the impossible - more than one book every year since the 1920s, every one a bestseller. So prolific was Agatha Christie's output - 66 crime novels, 20 plays, 6 romance books under a pseudonym and over 150 short stories - it was often claimed that she had a photographic memory. Was this true? Or did she resort over those 55 years to more mundane methods of working out her ingenious crimes? Following the death of Agatha's daughter,...