The Dunkirk dilemma, though central to Darkest Hour's storytelling and purpose, was really more of a subplot than anything. Actual Dunkirk is on-screen for less than ten minutes, and the subplot isn't completely resolved within the movie, instead leaving the viewer to figure out how it ended for themselves.
I know most people thought Dunkirk was fantastic, but I was disappointed in it, and all members of my family who saw it agreed. I suppose it was a case of unfulfilled expectations. But I immediately knew which film it was from the description. (Great quiz, BTW.)
"Movies based on a true story that were nominated for Best Picture, and also one called 'The Boys in the Boat'"