The true identity of the veiled lady hinges on the quality of her shoes. I often miss details like that, so when I got to the end, I went back to find a reference, probably understated, to the woman's footwear. I could find nothing. Now, I find that Agatha Chistie usually plays quite fair with her readers, in giving them the information from which to deduce a conclusion. This story seems to have cheated a bit.