I won't summarize the movie, as that would constitute a crime in the world of detective fiction. However, thank fully, I am glad that they have not distorted or played around with the stories or characters in these as they have with Miss Marple's movie adaptations, and the glimpse of the original is recognized.
The movie is decently made with Christie's trademark ensemble: a group of people, all with their own skeletons in the closet and lots of strings attached. Two murders and the suspicion of blackmail hovers in the air. Unfortunately, we see Poirot as a retired gentleman, now dedicated to the cultivation and improvement of vegetable marrows, a single masterpiece of which he smashes down in disappointment. We see a similar departure in the movie, where the truth emerges from confession, not detection. Although similar means of explanation have been used in other Christie stories, Poirot's train of thought has always gotten us there. One misses his little grey cells here.
The movie moves at the pace of a leisurely bicycle ride on a fine morning on a muddy road. The gravity of the loss of valuable human life rarely comes through ( an overdose of the British Stiff upper lip?), rather, it is merely a matter of logic, perhaps, with murder being Christie's recurring theme , the topic has reached a level of redundancy (should the director also approach murder thus?), the logic of the killer and the ingenuity of the detective assumes greater importance.
However, I'm sure, it would be of much greater literary pleasure to read through the book, since it offers something that the movie does not, a first hand exploration of the storytelling mind of the murderer. In which respect, the mystery stands, but the movie fails.