Her first novel, The Mysterious Affair at Styles, introduced Hercule Poirot the Belgian detective, who appears in a good number of Christie's novels. Hercule "died" in Curtain, one year before his creator, in 1975. The other principal detective, Ms. Jane Marple, an elderly spinster, first appeared in Murder at the Vicarage, in 1930. Secret Adversary is her second novel. Agatha wrote also six novels under the pseudonym of Mary Westmacott, two memoirs - one of which recounts her experiences in Syria with her second husband- and an autobiography that was published after her death. So many of her books were turned into theatre plays, that she eventually decided to try by herself. The Mousetrap (1952), is the longest running play in history with the record of 8862 performances at one single theater. Agatha was granted the title of Dame Commander of the British Empire in 1971. Five years later, when she died, Agatha was, and still remains to this day, the most successful murder mystery writer in the world.