Actress Jane Wilkinson approaches Hercule Poirot and pleads with him to speak to her husband, Lord Edgware, who is refusing to divorce her. The next morning Lord Edgware is found murdered and witnesses tell Poirot that Jane Wilkinson was the last person to see him alive. However, Jane was at a dinner party miles away at the time with twelve other guests who will testify to her being there. When two murders are committed, including that of famous impersonator Carlotta Adams, Poirot finds himself in the midst of one his most perplexing cases.