The part of Poirot had originally been intended for Zero Mostel but the film was delayed because Agatha Christie objected to the script. The film varies significantly from the novel and emphasises comedy, the specialty of director Frank Tashlin.
Albert Aachen is found dead, the murder weapon a poison dart. When a woman named Betty Barnard becomes the next victim, detective Hercule Poirot suspects that Sir Carmichael Clarke could be in grave danger.
As he and Captain Hastings look into the crimes, a beautiful woman with an interesting monogram named Amanda Beatrice Cross becomes the focus of their investigation, at least until she leaps into the Thames.