I would say understatement.
Example: You fall down the stairs and break your leg.While the ambulance is on the way, your friends asks how much it hurts and instead of wanting to seem like a crybaby you downplay how much pain you're actually in. Which is an understatement.
So when people make tragic movies there is always a theme to them or a goal the author is trying to get out. It might be a sad movie that a lot of bad things happen but in the end usually something good comes out of it and that can help people, or can even be more interesting, to be a successful story.
Third answer i think! let me know if its correct