Unlike most Christies this one has kind of a wacky plot. I'm still not sure how the fellow who was #4 got mixed up with the rest of them, given that he seemed to not move in the same circles. And he never seemed all that menacing to me. What made this one for me was the exploration of Poirot's & Hastings's friendship. I think you really get to see the depths of it here, how concerned they are for each other and how much each wants to keep the other safe.