As always, Agatha Christie uses brilliantly minute yet obvious once its pointed out details that reveal who the culprit is. It is highly admirable how she constantly brings new, yet no less clever, angles to her mysteries. I loved how Poirot knew that the chambermaid was behind the robbery and was not a real maid because the adjacent room to the crime had not been properly dusted. The text pointed out that the furniture had a thin layer of dust but I did not make this connection. As usual, Poirot noticed details that went over the reader's head. I love that Christie is still able to surprise me regardless of how many of her stories I read.
My biggest complaint for this story is how all the action happened off page. We witnessed Poirot briefly investigate the robbery, but then he developed a hunch and left for London, leaving our narrator Hastings alone at the hotel none the wiser about whodunit. We follow Hastings go out for lunch, meet up with some old friends, and putter around on his own while waiting for Poirot to return. Finally he finds the detective again only to be told that the case is over. Poirot proved his hunch, called the police, and the culprit was already revealed and arrested. It felt like we missed the payoff since the best part of a mystery is the grand reveal and takedown of the bad guy. Poirot summarized how he put the pieces together and called Inspector Japp, but this had the same effect as when I DNF a book and ask someone who finished it to relay what happened to me. I felt removed from the resolution and denied what the entire story was building towards. This made it a deeply unsatisfying ending and I would have been more annoyed had the story not been so short.
The other criticism to note is how the characters kept referring to Mrs. Opalsen as fat. They must have said this word half a dozen times in a 35 minute audiobook. Sure, this story was first published in 1923 when times were different, but it was still irritating and unnecessary to hear the character defined primarily by her size.
Overall this story was as clever as readers expect from Agatha Christie and brought the usual joys of reading her books. I especially enjoyed the short length of this installment since it was delightfully bite-sized. I felt deprived of the best part of the mystery when the resolution happened off page, so this was not the Queen of Crime's best work, but it was still a solid mystery and returning to these characters is always a good time.