Premise: The Pearls of the Crown (French: "Les Perles de la couronne" ) is a 1937 French comedy film of historically-based fiction by Sacha Guitry who plays four roles in it (many of the other performers play multiple roles, as well). Guitry's Jean Martin investigates the history of seven pearls, four of which end up on the crown of England, while the other three initially go missing.
Hypothesis: the plot of the movie is a romance