This is a fine Poirot, but a bit unusual in that there are no murders. Rather, it is espionage. Still, well done and, as usual, entertaining. There is a slight historical disconnect though. While clearly meant to be before the September, 1939, outbreak of World War II - the German ambassador is still in residence - the principals still refer to the "PM" and "Winnie" and "Eden" as if the Churchill war cabinet was in power. Of course, that didn't happen until May of 1940, 8 months after war had been declared. Not critical, but a goof not typical of this great series.