Right now I'm going to say The Killers with Burt Lancaster and Ava Gardner. Its a classic film noir thriller based on a short story by Ernest Hemmingway. This is a movie I would love to see Quentin Tarantino do a remake of. I happen to think its perfect for him.
I like the movie as much for the way the story is told, as much as the actual story itself. There's more I could say, but I'm going to go for concision, for a change. I have many more selections, but you only asked for one. I'm going to also follow instructions, for a change.
Take it light, David R. Bradley.