Vintage Poirot. As is almost always the case, you have to reach the very end of the book before you have any inkling as to who the murdered is. With Christie you can't adopt the Midsomer Murder trick of looking to see who is the least likely candidate and know that that almost certainly will turn out to be the murdered. In Christie's books it might or might not be the least likely person, or even someone beyond that! Or it might be a seemingly obvious person, but somehow she manages to put in so many twists and turns that you end up thinking it can't be. Genius. In this book you get many options - Secret Service, anarchists, family, financial motives, economic de-stablisation motives, personal motives and much more. I guarantee that you will not work out who the murderer is until Poirot, splendid as ever, reveals his, her or their identity/identities at the end. Superb.