Like all detective stories those of Agatha Christie, have one thing in common Red Herrings and her stories are quite literally replete with them.
In this particular episode I found myself, as per usual seemingly beset by them, until albeit late on matters appeared, to take on a somewhat startling clarity.
And I commenced to ask myself some questions, to what extent was Poirot enamoured of the Russian Countess? Sufficient to be involved in collusion?
What was in the red bag that she gave him?
Precisely why did Poirot hire the London detectives?
He clearly said the wasn't involved, in the case he hired them for.
Why did Poirot so assiduously distance, himself from the missing jewellery case?
Did he deliberately lead Hastings, and Miss Lemon on a wild goose chase?
When Poirot bid his farewell to the Countess, he made reference to other recent robberies, was he perhaps inferring that she, could possibly be accused of them?
What precisely mean when he, spoke of her returning to "Her business"?
There have certainly been fictional detective cases, where the culprit has been allowed to abscond, and deals have been allowed to facilitate this.
In Sherlock Holmes stories this has occurred, and I doubt that Agatha Christie was averse to such notions.
Where the protagonist may, for their own specific motives, consider that it served, some form of 'Higher calling'