A masterpiece of extra-precise murder-logic. Towards Zero 
was written during World War II, but the war is never mentioned – which gives a hint to Agatha’s method. Her books don’t take place in the real world; they’re fables of Englishness. This one includes a manor house with a convoluted floorplan – described, not reproduced in diagram form – numerous semi-comical guests, plus further visitors. Everyone, even the kitchen maid, is highly suspicious. (Especially the kitchen maid!)
Funny how in a book like this the English food seems to taste good. The British are so literary that their meals are intended to be described rather than eaten.