Having seen all the actors in this movie, in other movies, I was comfortable with them. I was not familiar with the novel of Ms. Christie. My first time watching the movie was in a drive-in. I fell asleep. However, I subsequently watched it over ten times and each time I've found it fascinating: the dialogue; the actors playing parts that I thought was unusual for them, etc. I now have it on DVR, forever. One of my all-time favorites.