If you loved Fat Man and Little Boy, try The Killing Fields
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Roland Joffé, and they both carry the dread, gut punch mood tags, and they sit in Drama / History / War territory. If that's the register that drew you to Fat Man and Little Boy, the second film will land in a comparable space — through a different lens.
dreadgut punch
What The Killing Fields is
You cover war from the streets of Cambodia until your evacuation order arrives. Then your fixer refuses to leave with you and the rebels roll into Phnom Penh. A seasoned observer notes how the camera lingers on a man who stays behind.

