A young woman named Carla approaches the famous detective Hercule Poirot. Her mother, convicted of murdering her husband sixteen years ago, is now preparing to marry and fears that the events of long ago could ruin her personal life. She insists, however, that her mother would never lie to her. And sixteen years ago, she declared herself innocent…

Captured by the complexity of the mystery, Poirot takes on the case—and discovers that five more people are suspected of the murder. And although so much time has passed, and Carla's mother's guilt is considered proven, Poirot's powerful intellect takes on the task…