Hm, I have to say, not my favorite Agatha Christie book. 
 What this book did extremely well was create tension and suspense. I couldn't put the book down and I was just as terrified and confused as the victims in the story. I was constantly wondering who would die next and who was committing the murders. I'm not giving this 5 stars because the big reveal kind of disappointed me in that it's a classic case of possible, but not really probable. I suppose it makes sense for the killer to be who it is. 
 Also, I'll pat myself on the back for having an idea of where this was going, (view spoiler)[ Since the first murder of Marston I had the idea that the killer would pretend to be killed off so they would be free of suspicion. Of course, I thought maybe it was Marston because he was the first to go, but alas I was wrong. (hide spoiler)]. 
 If anything this book is a quick, enjoyable read that will keep you on the edge of your seat.