Pyne was often fortunate enough to have the assistance of Mrs. Satterthwaite, and the ingenious Parker Pyne, who specialized not in solving murders, but in manipulating the lives of others so as to bring them happiness and/or adventure. Others who debuted during this experimental period were the weird pair of the other-worldly Harley Quin and his fussbudgety, oldmaidish "contact," Mr. Superintendent Battle, stolid, dependable, and hardworking, came onto the scene in The Secret of Chimneys (1925) and later solved The Seven Dials Mystery (1929), but probably because of a lack of charisma was relegated to a subordinate role after that. The enigmatic, laconic Colonel Race appeared first in The Man in the Brown Suit (1924), but, since his principal sphere of activity was the colonies, he was used only sporadically thereafter. Tuppence and Tommy Beresford, whose specialty was ferreting out espionage, made their debut in The Secret Adversary (1922) their insouciant, almost frivolous approach to detection provided a sharp contrast to that of Poirot. While writing in imitation of Conan Doyle, Christie experimented with a whole gallery of other sleuths. There is even a copy of Conan Doyle's ineffectual Inspector Lestrade in the person of Inspector Japp. Yet occasionally he wins applause from the master by making an observation which by its egregious stupidity illuminates some corner previously dark in the inner recesses of the great mind.
John Watson a retired military man, has much in common with his prototype: he is trusting, bumbling, and superingenuous, and by no means an intellectual. Like Holmes, Poirot is a convinced and convincing spokesman for the human rational faculty (he places his faith in "the little grey cells"), uses his long-suffering companion as a sort of echo-chamber, and even has a mysterious and exotically-named brother who works for the government. Her debt to the Sherlock Holmes stories of Sir Arthur Conan Doyle is manifest in the books in which this pair appears. It was in her first book, The Mysterious Affair at Styles (1920), that Christie introduced one of her two best-known detectives, Hercule Poirot, and his amanuensis, Captain Hastings. Her total output reached 93 books and 17 plays she was translated into 103 languages (even more than Shakespeare) and her sales have passed the 400 million mark and are still going strong.
In 1920 Christie launched a career which made her the most popular mystery writer of all time. Archibald Christie the marriage produced one daughter. Her family was comfortable, although not wealthy, and she was educated at home, with later study in Paris. The daughter of an American father and a British mother, Agatha Mary Clarissa Miller was born at Torquay in the United Kingdom on September 15, 1890. She also wrote romance novels under the name Mary Westmacott. Dame Agatha Christie (born Agatha Mary Clarissa Miller) was the best selling mystery author of all time and the only writer to have created two major detectives, Poirot and Marple, as well as having written the longest-running play in the modern theater, The Mousetrap.