This book has been listed as one of the 100 best mysteries ever written. It is full of twists and turns and you need to pay attention as you go along. It becomes not so much a "whodunnit" as a "why did it get done?" The ending scoops up all the little hints just tossed around at random along the way, and presents them in a neat and clever little package that makes you say "Well, of course! I should have seen that all along!"