Break out your best monocle because we're investigating the Queen of Crime. Agatha Christie essentially invented the modern murder mystery and is the best-selling writer of all time, with over 2 billion copies of her books sold. She also loved a good mystery, so when she disappeared on Dec 3rd, 1926, there was bound to be a twist to the story.

Sources
https://www.agathachristie.com/about-christie
https://en.wikipedia.org/wiki/Agatha_Christie
https://www.biography.com/writer/agatha-christie
https://www.historyextra.com/period/20th-century/agatha-christie-disappearance-mystery-facts-poirot-miss-marple-detective/