A Hercule Poirot Amuse-Bouche: The Adventure of the Italian Nobleman by Agatha Christie

This one is a comely little Christie puzzle that is definitely not
going to win any awards for ingenuity, but it's pleasant enough to
read. And to discuss. Warning: you might not want to sit down to
this one with a cup of coffee. Or a rice soufflé. Or any food,
really.... (That's not a spoiler: when Hercule Poirot stares at the
remains of a meal for as long as he does at the beginning of this
story, you know the meal has to be significant.)