I watched the 2017 Murder on the Orient Express film last night. After


is murdered, we find out that

he was actually Casetti

But how did Poirot know that?

At the time, it seemed like Poirot simply announced that that's who he was, and then started using that information to untangle the plot.

In particular, IIRC Poirot knew this before he found and filled in the partially burned note.

If I've merely misremembered the sequence of events, and he actually found the note first, then the letters he filled in to find Daisy Armstrong's name seems too implausible a leap, if there has been no prior link to the Armstrong case.

  • 2017 film. Though I'd be up for hearing how it played out in other versions.
    – Brondahl
    Dec 24, 2017 at 19:19
  • From Agatha Christie's point of view, it is plausible that a detective makes the relation with the affair of Cassetti, because it is a direct reference to the real life event of Lindbergh's baby kidnapping Apr 30 at 14:01

1 Answer 1


Poirot figured out the victim's true identity only after discovering partially destroyed threatening letters in the man's cabin after the murder. The letters referenced a famous recent child abduction and murder. Being a detective, and also having been asked by Mr Armstrong to help find his missing child, Poirot would have been interested in and familiar with the details of the famous case. Given the letters and the murder on the train, he correctly surmised that the victim of the crime he was investigating must have been the perpetrator of the abduction/murder mentioned in the letters.

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