The Mystery of the Blue Train is another Poirot mystery by Agatha Christie.  American millionaire Rufus Van Aldin has bought the famous Heart of Fire, among other massive rubies, as a little no-occasion gift for his daughter Ruth. When he goes to visit her and give her this gift, though, he can’t bear to see her unhappiness in her marriage, and Rufus tries to convince his daughter to  divorce her husband. This is old-time British divorce, which means private investigators and evidence of adultery, there’s no way to do a no-fault split. Ruth would like to be free of her cheating husband, but she’s worried that an investigation into her marriage will turn up not only her husband’s mistress, Mirelle, but her own friendship with Comte de la Roche.

The Van Aldins are loaded, of course, so the priceless rubies just seem like a typical gift from dear old Dad. In dollar princess style, father Rufus is a brash self-made man, daughter Ruth is a pretty American heiress, while his son-in-law Derek is heir to a title and an estate, with almost no cash. Derek will lose out a great deal if they divorce.

Ruth leaves town, pretending she’s meeting friends on the Riviera, but is actually heading off to meet up with Roche. Somehow Ruth, her husband Derek, and Derek’s mistress, Mirelle, all book rooms on the same Blue Train without seeing each other. When Ruth is found dead the next morning,  her husband, her ‘friend’, and her husband’s mistress all look guilty, with loads of shady acts and piles of contradictory evidence. Exactly what I like to read! Fortunately, our favorite Belgian detective also happens to be on that train.

Since the main action of The Mystery of the Blue Train takes place on a train, and there would be no mystery without the train, I chose this for “A book set on a plane, train, or cruise ship” for my PopSugar reading challenge.  The Blue Train is an upscale night train to Nice, and the stops on the train’s route, the layout of the compartments, and even the discussions in the train’s dining car are key to the mystery. A story about this luxe night train through France is a perfect read for these endless months of not-actual-lockdown-but-still-no-unnecessary-travel.

Katherine Grey, formerly a lady’s companion, is on the Blue Train that night as well, heading out to see distant cousins who’ve suddenly taken an interest in her now that she’s wealthy. I almost thought this was a joke character, since her backstory seems to reference other Christie stories and themes. She’s inherited a great deal of money from the women she looked after, a frequent device in these mysteries, but under thoroughly un-suspicious circumstances. Katherine’s also from St Mary Mead, a village where everyone says nothing ever happens, so apparently she and Ms. Marple never crossed paths. She’s unconnected with the murder, but begins to have feelings for someone and really wants a certain party cleared of suspicion.

Overall, this is a great mystery with affairs and missing jewels, where basically everyone is rich and bored. For a lot of the characters, a scandalous murder livens up just another day of lunching and tennis.

There is one thing I don’t love about some of these older mysteries. Poirot, and sometimes other characters, have the ability to look at someone and determine that they’re Jewish, and when a Jewish person is identified, they draw certain conclusions which are not exactly about giving someone the high holidays off from work.  So The Mystery of the Blue Train is another mystery with sneaky, connected, Jewish gem dealers. While this is hardly the worst Jewish stereotype in older fiction (and it’s not even the cringiest dated idea in Christie novels!), it’s not my favorite, either.