“Papa Poirot, he always laughs the last.”

The thing about Agatha Christie is that she has a book for every season – the chilly Crooked House for summer, Evil Under the Sun for winter, and the puzzling The Mystery of the Blue Train for a rainy day.

Published in 1928, The Mystery of the Blue Train is the sixth Christie mystery featuring detective Hercule Poirot. Despite his early appearance, we meet Poirot at the height of his powers as he gracefully solves the mystery of a robbery and a murder.

The Blue Train, also known as the Millionaire Train, is on its way to Nice from Paris. As the name suggests, the train ride serves as a pre-vacation for the very rich before they arrive at the sunny paradise of the French Riviera. The train is carrying the elite of many races – the British who are prim and proper, the French who are often moody, the Russians who have a taste for fine things, and the Americans who are unapologetically money-minded.

A robbery (and a murder!)

But the person of interest to us is Ruth Kettering, an American heiress and daughter of millionaire Van Aldin. She is carrying a set of blood-red rubies, the most precious of which is “Heart of Fire”. The apple of her father’s eyes, Ruth is aware of the tremendous value of her existence – and, of death. She has been told to divorce her good-for-nothing husband Derek Kettering, which barely discomforts her, for she is in love with Comte de la Roche – a French aristocrat whom her father strictly disapproves of. The shadows of the three men loom large on Ruth, and she worries the train ride will not end happily.

She confides in English spinster Katherine Grey who has been a companion to old women, children, and pets and has finally had some time to take a break after long years of service. She is sensible and upright and has caught the fancy of men who have been looking to settle down after the thrilling affairs of their youth.

The sensibility of the English against the excitability of the American presents an interesting contrast – perhaps in line with the times when Christie was writing. The former stood for a long tradition of class and respectability while the latter, also the nouveau richer, is yet to master these subtleties of human expression. They are flanked by self-important officials, secretive maids and butlers, and those who flit in and out of shadows.

When the train arrives at Nice, Ruth’s foreshadowing comes true. Her jewels are stolen. Additionally, she turns up dead. And to make matters even worse, someone has caved her face in and disfigured it beyond recognition. The dead heiress is identified by Katherine who remembers her build and the outfit she wore the night before.

Enter Hercule Poirot

The investigations by the French police are rushed and they are itching to pin the blame on Ruth’s husband, who stands to gain two million pounds in the event of her death. The rubies he has surely stolen will add to the windfall. Van Aldin’s clear dislike for his son-in-law emboldens the police. But the answer is never so simple, is it?

We know that. And so does Hercule Poirot. He cautions against haste and urges due diligence before implicating someone in murder, no matter how seedy a character they might be. As Poirot puts every passenger under the microscope – and those who weren’t on the train at all – he becomes confident that the murder is not as straightforward as it seems. Poirot’s entry into the investigation means the reader is inevitably thrown off the track – we get only half glimpses into his mind at work, we catch the conversations midway, and are allowed to put only one foot into the private chambers of the suspects.

Poirot is driven around in circles, he’s the only cat in a basket full of mice. As the mystery mounts and tangential questions are raised, Poirot cashes in a favour owed to him from seventeen years to nab the culprit. Is it a singular mind at work or is it a nefarious network of crooks out to get a helpless woman? Only the “little man with an egg-shaped head” who “moralises”, “philosophises” and “reflects” will be able to tell.

The grimness of the story is allayed by Poirot’s boastful remarks about himself which, though intended to be sincere, made me chuckle. For instance, when a man confesses he has not heard of Poirot, the offended detective quips: “Permit me to say that you have been badly educated. It is the name of one of the great ones of this world.” I have found Christie’s tendency to take her protagonist lightly – and occasionally poke fun at him – to be a superb display of her whip-sharp humour.

Like all Christie mysteries, the fun lies in the blind spots she pushes the reader into. I have never attempted to solve the mysteries and prefer being led by the author. Therefore, solely as a member of the audience, I enjoyed reading about the many minor characters that appear in the novel. Some descriptions are decidedly racist and the male characters have less-than-generous views of women, still, Christie is the product of her time. She has undergone revision for the aforementioned lapses in her novels. But, as far as I’m concerned, this does little besides tampering with the quality of prose and injecting moral righteousness where perhaps there is no need for it.

The Blue Train chugs along nicely and the savage winds of suspicion and death do not derail it. The climax, when it comes, is delicious – a satisfying conclusion to an otherwise macabre journey. As for Poirot, as per his admission, he might very well be the “greatest detective in the world”. And I, for one, happily agree.

The Mystery of the Blue Train, Agatha Christie, HarperCollins.