Short answers, pulled from the story.
Agatha Christie disappeared on the 3rd of December 1926 and was found at the Swan Hydropathic Hotel in Harrogate, Yorkshire, on the 14th of December 1926. She was registered under the name Mrs Tressa Neele, the surname of her husband's lover, and from South Africa.
Agatha Christie gained knowledge of poisons while serving as a volunteer nurse and qualified apothecary's assistant in the Town Hall Red Cross Hospital in Torquay between 1914 and 1918. She worked 3,400 hours and used real substances like arsenic, strychnine, digitalis, and thallium to dispatch victims in her fiction.
Agatha Christie traveled to excavation sites in Syria and Iraq with her husband Max Mallowan starting in 1930, visiting places like Ur, Nineveh, Tell Arpachiyah, Chagar Bazar, Tell Brak, and Nimrud. She also took side trips to Italy, Greece, Egypt, Iran, and the Soviet Union, which provided settings for novels such as Murder on the Orient Express and Death on the Nile.
Agatha Christie is the best-selling fiction writer of all time with her novels having sold more than two billion copies in 44 languages. Her novel And Then There Were None is one of the top-selling books of all time with approximately 100 million copies sold.
Agatha Christie's stage play The Mousetrap has been performed in the West End of London since the 25th of November 1952. The play holds the world record for the longest initial run with more than 27,500 performances by 2018.