Japp's career in the Poirot novels extends into the 1930s but, like Hastings, he disappeared from Christie's writing thereafter.
This is the first of the Poirot novels in which lesbianism (between a woman and her companion) is discussed as a possible motive.
As a result, Suchet will have performed adaptions of all Poirot novels and short stories.
She published thirteen Poirot novels between 1935 and 1942 out of a total of eighteen novels in that period.
By contrast, she published only two Poirot novels in the next eight years, indicating the possibility that she was experiencing some frustration with her most popular character.
As a result, Suchet will have filmed adaptations of every Poirot novel, and all but one Poirot short story.
But if Dame Agatha is long dead and a new Poirot novel appears, whodunit?
Mr. Goby is a recurring character in many of the later Poirot novels.
Of the fifteen Poirot novels published between 1920 and 1937, he appears in six.
They meet in the story Murder on the Links, the second full-length Poirot novel.
