Alibi is a 1928 play by British mystery writer Agatha Christie that was adapted into a movie in 1931. 1928 (MCMXXVIII) was a leap year starting on Sunday (link will take you to calendar). ... Agatha Mary Clarissa, Lady Mallowan, DBE (15 September 1890 â 12 January 1976), better known as Dame Agatha Christie, was an English crime fiction writer. ...