Original Airdate: 10 February 1991 Written by:Anthony Horowitz Directed by: Andrew Piddington Recurring cast: Captain Hastings, Inspector Japp, Miss Lemon
Tropes
Adaptational Name Change: Lady Runcorn's maiden name in the episode is Beatrice Palmerston, which serves as another Red Herring meant to throw off the investigation.
Bilingual Bonus: The resolution of the case depends on the fact that the letters "BP" in Cyrillic correspond to the letters "VR" in Latin. This means that neither Bernard Parker nor Lady Runcorn (maiden name Beatrice Palmerston) stole the necklace, but Countess Vera Rossakoff.
Book Ends: The starts in a train station on Countess Vera Rossakoff's arrival, and ends on the same station at her departure.
Hastings: [referring to marriage] You ever thought about it?
Poirot: In my experience, I know of five cases of wives being murdered by their devoted husbands.
Hastings: Oh?
Poirot: And twenty-two husbands being murdered by their devoted wives. So thank you, no. Marriage, it is not for me.
Dating Catwoman: Poirot and the Countess Rossakoff, though he realizes it is not a sustainable romance.
He's Got a Weapon!: As Hastings and Miss Lemon encounter a tramp (played by Redfern, one of the private detectives Poirot hires for the Countess), he pulls out a gun, and Lemon shouts out, "Hastings, he's got a gun!!!" before the tramp fires the weapon at him. Hastings, of course, is not killed, but only damaged his forehead in escaping from the shots.
Let Off by the Detective: Even if Poirot figured out who the jewel thief is, he decides to let her off, but on the condition that their paths never meet again.
O.O.C. Is Serious Business: Hastings and the others are worried that Poirot is focusing on entertaining Countess Vera Rossakoff rather than investigating who stole the necklace.
Title Drop: When returning the Countess' cigarette case, he identifies it as the titular object because of the dual meaning of the inscribed initials.
Train-Station Goodbye: Poirot and the Countess, as he sends her on her way, both waving each other goodbye.
Alternative Title(s):Poirot S 0307 The Double Clue
