About halfway through I figured out who did it. I´m super excited. Nonetheless I´m a bit disappointed by the ending, because
But then, it´s been so nice to revisit Poirot, who is as odd, brilliant and eccentric as ever:
"Hercule Poirot does not run the risk of disarranging his costume without being sure of attaining his object. To do so would be ridiculous and absurd. I am never ridiculous."