"A Moment Later a Cry Rang Out into the Night, and the Great Train Came to An Unwilling Halt in Obedience to the Imperative Jerking of the Communication-Cord"

"The Plymouth Express Affair."
By Agatha Christie (1890-1976).
First appearance: The Sketch, April 4, 1923 (as "The 
Mystery of the Plymouth Express").
Reprinted in The Blue Book Magazine, January 1924 
and October 1941.
Collected in The Under Dog and Other Stories (1951) 
and Poirot's Early Cases (1974).
Filmed for TV in 1991 (HERE and HERE—for now).
Short story (7 pages, 1 illo).
Online at The Pulp Magazine Project (Flip Book HERE) 
or (PDF, slow load, HERE; scroll down to PDF page 142, 
text page 136).

"'The little grey cells,' so often referred to by the great detective Hercule Poirot, certainly get in their fine-work in this intriguing mystery story by an exception-ally talented writer."

For Alec Simpson, Royal Navy, it should have been just another ordinary train trip to Plymouth, but that body—chloroformed, stabbed, and then stuffed under the carriage 
seat—makes it anything but ordinary. When the victim's father, a wealthy magnate ("the 
steel king of America"), summons Hercule Poirot to investigate, the diminutive Belgian 
soon perceives larger dimensions to the situation, including a missing case holding a hundred thousand dollars' worth of jewelry; "an unprincipled scoundrel" who stands to inherit the victim's fortune; an amorous French nobleman ("an adventurer of the worst 
type"); and an altogether too obvious fashion statement ("a coat and skirt of bright blue frieze, and a small toque of white fox fur"). By story's end, however, the fastidious sleuth 
will be able to declare: "It was of the most simple."

The Challenge to the Reader:
    ("It is suggested that the reader pause in his perusal of the story at this point, make 
his own solution of the mystery—and then see how close he comes to that of the author.
— The Editors.")

Poirotisms:
   ". . . to track footmarks, and recognize cigarette-ash is not sufficient for a detective. He must also be a good psychologist!"

   "Japp is the 'younger generation knocking on the door.' And ma foi! They are so busy knocking that they do not notice that the door is open!"

Comment: Unlike the filmed version, in the story neither Poirot nor the narrator Hastings ever gets near a train station.
Typo: "wont" [for won't a couple of times]

Resource:
- Our last railway-related crime story is (HERE).

The bottom line: “I should fancy, however, that murder is always a mistake. One should never do anything that one cannot talk about after dinner.”
   ― Wilde