The Sins of Prince Saradine - short story from The Innocence of Father Brown.
Father Brown and Flambeau are on a little vacation in Norfolk, invited to visit the mysterious Prince Saradine. It doesn’t go well. Sure, Flambeau gets some good fishing in, but there’s also a duel with rapiers, a couple murders, a hanging, a case of mistaken identity, an awkward family reunion, and a gang of surly Sicilians.
"The Sins of Prince Saradine" offers no satisfactory resolution, a fair amount of holes in the plot, and a singularly inactive detective. Instead, it is more focused on twisty moral points, absurd instances of humor, and heavy-handed symbolism.