She was played by Vanessa Redgrave in Agatha (1979). Redgrave previously played Mary Debenham in Murder on the Orient Express (1974), an adaptation of her 1934 novel of the same name.
Crime is terribly revealing. Try and vary your methods as you will, your tastes, your habits, your attitude of mind, and your soul is revealed by your actions.
All her books and short stories feature some kind of plot twist or surprising ending with the least expected person being the bad guy.
The Queen of Crime
Agatha Mary Clarissa Miller
Torquay, Devon, England, UK
Wallingford, Oxfordshire, England, UK