SOPHIE HANNAH is the New York Times bestselling author of numerous psychological thrillers, which have been published in 51 countries and adapted for television, as well as The Monogram Murders, the first Hercule Poirot novel authorized by the estate of Agatha Christie, and its sequels Closed Casket, The Mystery of Three Quarters, and The Killings at Kingfisher Hill. Sophie is also the author of a self-help book, How to Hold a Grudge, and hosts the podcast of the same name. She lives in Cambridge, UK. Agatha Christie is the most widely published author of all time, outsold only by the Bible and Shakespeare. Her books have sold more than a billion copies in English and another billion in a hundred foreign languages. She died in 1976, after a prolific career spanning six decades.