It's a tale on 3 USN aviators stuck on a raft, proverbially in the middle of nowhere somewhere in the S Pacific after their plane ran out of fuel while flying a patrol mission. It's a movie I've waited 50 years to see, having read the book it is based on "The Raft" when I was a kid. My dad didn't read too many books, he simply didn't have the time, but having served on PBY patrol planes in the USN in WW2 that flew in the S Pacific and the Caribbean he was no doubt fascinated by the subject. I'm sure it was the worst nightmare that an aviator or sailor could imagine, being stuck on a raft without water or food, virtually no hope of being spotted by a rescue plane and I'm sure that these young men speculated during the endlessly boring patrols they flew, on the complete futility of such a situation.
And that's what "Against the Sun" is about. 3 actors on a raft and if you have no interest in this type of story, you will be bored to tears. At 100 minutes it comes in at about an appropriate running length although .10-15 minutes could have easily been cut. Then again the director could have unnecessarily added about .15-20 minutes with back story or scenes involving the crew from the carrier "Enterprise" (which the flew from) or with their families back in the States after they've been advised that they are missing at sea. Works fine at it is. Good performances by the 3 actors involved, probably not easy to do. I hope all of the 3 real life aviators had good lives, they earned it. I'm sure they appreciated every day life gave them.