Poirot was silent a minute. Then he said: “If you will be so good, M. Hardman, assemble everyone here. There are two possible solutions of this case. I want to lay them both before you all.”I had not actually read this Agatha Christie novel before, though of course I knew whodunnit as it has been widely spoilered in popular culture. There is still a thrill in watching the insanely convoluted plot (both story and conspiracy) come together, and I patted myself on the back for picking up the one clue that Poirot misses (the monogrammed handkerchief). It's also interesting for just how much the backstory draws on the real-life Lindbergh kidnapping, which had happened two years before the book's publication; the similarities will not have been lost on the contemporary audience. The resolution does require impressive ability to deceive Poirot, at least initially, on the part of those responsible, and his moral choice at the end is a bit questionable (though not the only time this happens; I shall be keeping count).
But there is extra fascination for today's reader in the locations described. The opening scene of the book is the railway station in Aleppo, where Poirot is joining the train that started in Baghdad (with a break between Kirkuk and Nisibis). It's extraordinary for us now to imagine that route being a relatively unremarkable train journey, the year after Hitler took power in Germany. (Agatha Christie of course knew it well because of her visits to husband's excavations near Nineveh.)
For me the setting came even closer to personal experience when I realised that the actual murder takes place just outside Vinkovci, which I knew in 1998 as a traumatised frontline town recovering painfully from the recent conflict. In December of that year, with wife and small child, I drove past Vinkovci on the former Highway of Brotherhood and Unity through heavy snow, got turned back at the Serbian frontier after navigating the minefields, and finally found a hotel bed in the smashed urban moonscape of Vukovar. So although the area around the likely scene of the crime is actually fairly densely populated, I did feel shudders of sympathy. (See also Saki's short story, "The Name Day", for another creepy story of being stuck in a snowbound train carriage in the future Yugoslavia.)
I think as a mystery novel this is actually better than And Then There Were None; the story is more representative of the genre, there is somewhat less overt racism (gosh, a sympathetic Jewish character!), and the plot is slightly less implausible. I admit that these are fairly fine grades of distinction.