Agatha Mary Clarissa Miller Christie Mallowan, b. 1890, Torquay, Devon, England; d. 1976, Wallingford, Berkshire, England. Agatha Miller was brought up in South England, the second daughter of an English mother and an originally American father. She married at 24 to Capt. Archie Christie, and wrote her first detective story while serving as a nurse during World War I (The Mysterious Affair at Styles, published in 1920).
Following the publication of Styles-- which remains one of her best books-- she produced a handful of weaker books (mostly non-detective or adventure), but wrote many excellent short stories; then, in 1925, her fame suddenly increased with the success of her masterpiece of misdirection The Murder of Roger Ackroyd. By this time her marriage was growing unhappy, and in 1926 her husband ran off with another woman and asked her for a divorce. She suffered a breakdown and disappeared for ten days, when she was discovered (after a nationwide manhunt) at a hotel in the Lake District, claiming to have suffered amnesia. Whatever the truth, her fiction received a lot of publicity, and she and Capt. Christie were divorced in 1928. She met the archaeologist Max Mallowan while travelling in the Middle East a year later, and married him in 1930. Meanwhile, her writing had entered an inventive new phase, with several new detectives created, and between about 1931 and 1945 she produced most of the classic books of her career, concentrating on Poirot until about 1942, when she began developing Miss Marple's career. For the rest of her long life, she wrote prolifically, joined Mallowan on his yearly digs, and tried to avoid the public eye, which became more difficult as her fame grew. She was awarded the CBE in 1956, and made a Dame Commander of the British Empire (the female equivalent of a knighthood) in 1971. Her last novel, Postern of Fate, was written in 1973, when she was 82 years old. After about the 1950s, as pressure for quantity from her publishers combined with her own aging, her books generally declined in quality, though there are some exceptions, particularly involving Poirot.
During most of her career, Christie wrote at least one novel a year, ending with a total of 66; the last one published was Sleeping Murder, which appeared after her death. Another 21 volumes of short stories, mostly published in the 1940s and 50s, round out the catalogue, but these are harder to count properly, since many of the 145 stories were repeated in more than one collection. She also wrote (or adapted from her stories) 15 plays, of which all but one have mystery plots. (Between 1930 and 1956 she also published six romantic novels, under the name Mary Westmacott, and there are five more books of autobiography and poetry.)
Most of the novels star either Hercule Poirot, Miss Jane Marple, or the husband-and-wife team of Thomas and Prudence Beresford, known as "Tommy and Tuppence". Poirot, a retired detective from the Belgian Police Force practising as a private investigator in London, is fanatically neat and well-dressed, vain and egotistical, with an "egg-shaped head" and elaborate moustaches. He first appeared in Christie's first novel, The Mysterious Affair at Styles, in 1920 (together with his occasional sidekick and biographer, Capt. Arthur Hastings) and went on to star in a total of 33 novels (8 of them with Hastings) and 53 short stories in 10 volumes before his death, in Curtain, at perhaps age 85 or so. Miss Marple, an elderly spinster who uses her knowledge of human experience gained in a long village life in St. Mary Mead to solve crimes, is featured in 12 novels and 20 short stories in 7 collections, and arrived at the scene ten years after Poirot (in Murder at the Vicarage). She ages somewhat over the years, and is very old in Nemesis, but Sleeping Murder, published posthumously and subtitled "Miss Marple's Last Case", was actually written decades earlier, and does not fit the chronology. Tommy and Tuppence Beresford occupy 4 novels and a book of stories; we first meet them as sweethearts in 1922 (The Secret Adversary), and they age naturally, appearing as an elderly married couple in 1973 (Postern of Fate). The remainder of the novels and story collections have various one-time heroes or none at all, although a number of characters recur from time to time.
There continue to be Christie discoveries. A handful of short stories from the 1920s were unearthed in 1997 and published as While the Light Lasts in the UK and (together with an uncollected 1971 Harley Quin story) as The Harlequin Tea Set in the US. In the late 1990s several original Christie plays were adapted into novels by Charles Osborne and marketed as 'new' books. Christie was also a contributing author of three Detection Club stories: she was one of 14 contributors to The Floating Admiral (published by George Doran, 1931), Scoop (6 authors, serialized 1931) and Behind the Screen (6 authors, serialized 1930). These stories are collaborative mysteries in which each author wrote a chapter without knowing the plot intentions of the others.