Ingenious! The fast-paced plot was electrifying as the characters race against time to catch a cold-blooded serial killer on the loose. I love the complexity of this case as the whole country is involved this time. Anyone can be the killer! A breath of fresh air from the usual locked room mysteries where a limited number of suspects are involved. The twists and turns kept me reading till the shocking finale. Just when you thought you know who the killer is, Christie will always surprise you with the killer's true identity. I'd say this is one of her best Poirot novels.