This 1939 novel has been compared to the 1930 STRONG POISON by Dorothy Sayers. Both novels begin with the courtroom observations of a young woman accused of murder by poisoning. Both young women are befriended by a young man who sets out to clear her of the crime and fall in love with her in the process. Christie's rescuer is named Peter Lord while Sayers' is, of course, Lord Peter. Even with these similarities the two stories, although both excellent, are vastly different.
Elinor Carlisle had an understanding with her cousin-by-marriage Roderick Welman, that one day they would wed, live happily in their mutual Aunt Laura's country house with her considerable fortune somehow split between them. The plan suited them all, Elinor, Roddy and Aunt Laura. Aunt Laura was now in failing health and was being cared for by nurses, her servants, a doctor and Mary, a young woman who had grown up on the estate and of whom Aunt Laura had always been quite fond...perhaps too fond for Elinor and Roddy's own good.
Aunt Laura died, not to anyone's surprise but had left no will, much to everyone's surprise. As her only living blood relative Elinor inherited everything - lucky Elinor! Except Mary was so lovely, and Roddy so smitten with her that the engagement was called off. Then Mary died, of poison and Elinor was the only one of could have committed the crime.
Dr. Lord made an impassioned plea to Hercule Poirot to prove Elinor innocent - if she was in fact innocent. Poirot reluctantly agrees and begins to sort through motives, love affairs and long buried secrets to arrive at the truth.
The opening is dramatic altough it causes the problem of making the most sympathetic character, Mary, known to the read as the victim. The questions remain, however, of who did it, why, and how for the reader to try to puzzle through before Poirot reveals all.