The Mysterious Affair at Styles isn't just Agatha Christie's first Poirot novel, it was the only Poirot novel in the public domain until 2019. It was written on a bet that Christie couldn't write a detective novel in which the reader couldn't deduce the criminal. Her attempt laid the foundation for one of literature's most famous detectives.In this novel we're introduced to Poirot as he's settling in to a new life in England. After a woman is murdered at the country estate he's visiting, he has to use his detective skills to catch the criminal. The Mysterious Affair at Styles sets the stage for the Golden Age of Detective Fiction, and has everything you'd expect from a story rich in those classic detective fiction tropes.
