In Agatha Christie's short story, "The Double Clue," Poirot investigates the robbery of a collection of medieval jewelry from the safe of a dealer - including a necklace said to have belonged to Catherine de' Medici! Since the theft occurred during a dinner party, the suspects could be any of the guests. But which one? This short story originally appeared in the December 5, 1923, issue of "The Sketch" magazine. PS. We get to meet Countess Vera Rossakoff once again! One of the author's great minor characters. Librarian's note: this entry is for the story, "The Double Clue." Collections of short stories by the author can be found elsewhere on Goodreads. Individual entries for all Poirot short stories can be found by searching Goodreads for: "a Hercule Poirot Short Story."