Agatha Christie was the younger child of Frederick Alvah Miller, a well-to-do American business man living in England, and his Anglo-Irish wife, Clarissa Boehmer (1855-1926), called Clara, who wrote stories and poetry. Agatha had a sister, Margaret Frary Miller (1879-1950), called Madge, twelve years her senior, and a brother, Louis Montant Miller (1880-1929), called Monty, ten years older than Agatha.
The Miller children grew up at Ashfield, their parents' house on the outskirts of the seaside town of Torquay, in Devon. Agatha and Madge were born there, but Monty in New York. Clara had a brother, Captain Frederick Boehmer, who lived in London. The Millers were both rich and respectable - Frederick paid for the building of All Saints' parish chuurch, Torre, where Agatha was baptized.
The two girls did not go to school, but had tutors at home. Their father died when Agatha was eleven, and about this time she struck up a friendship with the novelist Eden Phillpotts, who lived nearby, and Madge got married. Phillpotts acted as a kind of tutor, guiding Agatha's reading. In her late teens, she went to a finishing school in Paris, where she studied music and was considered good enough to make a career as a concert pianist, but this did not appeal to her.
After Paris, Agatha spent three months in Egypt with her mother and became engaged to Reginald Lucy, a major in the Royal Artillery. She returned to England in 1912 and met Archibald Christie, of the Royal Field Artillery, later a pilot in the Royal Flying Corps. Soon after the outbreak of the Great War (on Christmas Eve, 1914) they were married at Bristol. While Archie was away fighting, Agatha worked at a hospital dispensary at Torquay. The theft of a quantity of arsenic prompted her to write her first book, The Mysterious Affair at Styles, and Hercule Poirot was born. She sent the typescript off to a publisher, who replied two years later that he wanted to publish it. In the mean time, the War ended and in 1919 Agatha's only child, Rosalind Christie, was born.
The first Poirot novel was a big success, and more books quickly followed, establishing Agatha as a well-known thriller writer. In 1922, Archie and Agatha made a long cruise to Madeira, South Africa, Australia, New Zealand, Hawaii, Canada, and the United States, leaving Rosalind at home with Madge.
On December 3rd, 1926, after crashing her car, Agatha vanished without trace from her home in Berkshire and was gone for eleven days, causing a sensation. Archie was questioned by the police on suspicion of murder, then the police found Agatha alive and well at Harrogate in Yorkshire, living under the name of her husband's mistress, Nancy Nelle. After her return, her family insisted that it had all been a case of amnesia, but the episode has remained a great mystery on which biographers still try to throw light. It now seems likely that Agatha planned to punish her unfaithful husband, but the whole thing ran out of control and backfired on her. In any event, Archie and Agatha soon separated and were divorced in 1928.
In 1930, Agatha met (at Ur in what is now Iraq) archaeologist Max Mallowan, later Sir Max. A Fellow of All Souls College, Oxford, and fourteen years younger than Agatha, he fell in love with her and she married him the same year, settling near Oxford and staying with him for the rest of her life. During the 1930s and 1940s, Agatha accompanied Max on his summer archaeological digs, mostly in the Middle East.
During the Second World War, Max was posted to Egypt and Tripolitania, while Agatha lived in London and worked as a dispenser at University College Hospital. In 1941, Agatha's daughter Rosalind married a serving soldier, Major Hubert de Burgh Pritchard, and Rosalind's only child, Matthew Pritchard, was born in 1943. Hubert Pritchard was killed on active service in France the next year, and Rosalind later (1949) married Anthony Hicks, a lawyer.
Agatha Christie's books are now said to have sold over one thousand million copies worldwide. She wrote seventy-eight thrillers, nineteen plays, two autobiographies, one book for children, and over one hundred short stories under her own name, plus six romantic novels under the pen-name of Mary Westmacott. Her career as a playwright began after the Second World War, and her The Mousetrap is now the longest-running stage production in the world, having opened in 1952, more than fifty years ago. Agatha's books and plays have built a very large family fortune for her descendants - Rosalind and Matthew are now estimated to be worth more than £600,000,000.
With Archie, Agatha lived for two years at Scotswood, Sunningdale, Berkshire, then bought a bigger house at Sunningdale which they called Styles in honour of Agatha's first book. She also had a London flat at 8, Addison Mansions, Kensington. Agatha and Max had two principal houses, Winterbrook House, Wallingford, Berkshire, a modest Queen Anne country house bought in 1934, where they remained until their deaths, and Greenway House on the Dart estuary in Devon, a property of about two hundred and fifty acres bought as a summer home in 1938 and still owned by the family.
Agatha was appointed a Fellow of the Royal Society of Literature (1950), a Commander of the Order of the British Empire (1956), and a Doctor of Letters of the University of Exeter (1961). She served as president of the British Detection Club. Just five years before her death, she was appointed a Dame Commander of the Order of the British Empire, the female equivalent of a knighthood, giving her the title of 'Dame Agatha'. She died in 1976, and is buried at St Mary's Church, Cholsey.