Mr Opalsen is now a theatre impresario instead of an oil mogul, while his wife is now a stage actress.
The thief is changed from the chamberlain of the hotel to Saunders, the Opalsens' chauffeur.
Batman Gambit: Poirot has Mr Opalsen arrested on suspicion of staging the theft of the pearls as part of an insurance fraud scam, and implies that the pearls are likely a fake. It's all a ploy meant to smoke out the real thieves, who would then return to where they stowed the pearls away to check.
Busman's Holiday: Poirot is advised to take a vacation in order to rest his "little grey cells", but soon finds himself embroiled in a jewelry theft.
Contrived Coincidence: Poirot and Hastings' room is right across the room of the Opalsens, who quickly strike up a relationship with the detective.
"Eureka!" Moment: Poirot gets one when he asks Celestine how she met Andrew, when she reveals that they met on a production of The Importance of Being Earnest. Said play had a character named Worthing, which confirms Poirot's suspicions.
Poirot complains about his name being used to drum up publicity for the play, Mr Opalsen replies as such:
Mr Opalsen: [But] a man in my position needs all the publicity he can get.
Later on, when Poirot has Mr Opalsen arrested as part of his plan to uncover the thieves, he gets back:
Poirot: But, Mr Opalsen, a man in your position needs all the publicity he can get.
Once More, with Clarity: When Poirot does the summation, he points out that he was relying on several details that Japp had missed in his investigation, with the story going back to the scenes where he found the evidence he needed.
Running Gag: Poirot keeps on getting mistaken for a Lucky Len, who was employed by the local paper as part of a promo it ran. Getting mistaken for Lucky Len one too many times leads to Poirot deciding to investigate after initially refusing to do so.
"Shaggy Dog" Story: Poirot finally runs into the real Lucky Len at the end of the episode, who happens to have a similar mustache to his (which was why Poirot kept on getting mistaken for him). Unfortunately for Poirot, Lucky Len was already fired by the paper, so the ten guineas would be a moot point.
Spotting the Thread: Poirot is immediately suspicious of Mr Worthing, because in spite of walking with a cane and a limp he decides to take the stairs rather than the elevator to his room.
Tempting Fate: Mr Opalsen brags that the pearls, acquired from the collection of the former Tsar of Russia, wouldn't be stolen. Of course, as the title of the story implies, that's not gonna be the case.
Wolf in Sheep's Clothing: Saunders, the mild-mannered chauffeur, turns out to be the same person as Mr Worthing, the thief who stole the Opalsens' pearls.
