When Elinor Carlisle is accused of poisoning her romantic rival, Hercule Poirot must navigate a web of inheritance, jealousy, and hidden motives to uncover the truth before the executioner claims his prize. Elinor stands trial for the murder of Mary Gerrard, facing a mountain of circumstantial evidence that points solely to her guilt. As the primary beneficiary of a contested estate, she possesses both the motive and the means, leaving her with few allies in a courtroom convinced of her culpability. The narrative follows Poirot as he reconstructs the events leading up to the crime, employing his trademark psychological acuity to challenge the prosecution's seemingly airtight case. Through a series of interviews and meticulous observation, the detective works to dismantle the facade of the courtroom drama and reveal the actual perpetrator.

This novel is widely regarded as a quintessential example of Christie's ability to blend courtroom drama with the traditional detective puzzle. Readers often highlight the psychological depth of the characters, noting that the mystery relies as much on human nature as it does on physical clues. The pacing is frequently praised for its steady build toward a revelation that challenges the reader's initial assumptions about the accused. It remains a staple of the Hercule Poirot series, valued for its intricate plotting and the clever subversion of standard murder trial tropes.