Agatha's writing career took off in 1920 with the publication of her first novel, "The Mysterious Affair at Styles." This novel introduced the iconic detective character, Hercule Poirot, who would go on to feature in 33 of her novels and 54 short stories.

In 1914, Agatha married Archibald Christie, a Royal Flying Corps officer, and they had a daughter, Rosalind, in 1919. The marriage was happy, but Archibald's infidelity and subsequent request for a divorce in 1927 devastated Agatha. This period of her life was marked by depression, anxiety, and a sense of disorientation.

The 1920s and 1930s are often referred to as the "Golden Age" of detective fiction. Agatha Christie, along with other writers like Dorothy L. Sayers and G.K. Chesterton, helped shape the genre. Her novels, with their clever plots, memorable characters, and social commentary, transported readers to a world of mystery and intrigue.