This story, published in 1934, was next on my list of Agatha Christie novels in order that I'm going through. The book begins with a dinner party in which someone drinks a poisoned cocktail and dies... or was it an accident?
It's a Hercule Poirot mystery, but in this story other characters are allowed to do a little more sleuthing than usual. As always, the ending is a real surprise!
I also read recently by this author: Why Didn't They Ask Evans?