It’s a movie about a guy named Charlie with a boat and a British Methodist missionary woman named Rose who asks his help to blow up a German gunboat (it was WW I) down the river.
It’s unclear why a missionary was the best choice to blow up a German gunboat, but I suppose that’s why they made it into a movie.
The “African Queen” was the name of the boat, not (as I thought) a female monarch from Nigeria nor a cross dresser from Kenya.
Now Charlie does many courageous things to get the woman who needed a ride (and help) on her suicide mission and she shows her appreciation by dumping out all of his liquor and insisting he remain sober.
Anyway, they sail down the river and ready the boat for battle, but high winds and other boat-related complications (holes) sink the boat.
So now Charlie has no boat and no booze.
To pile it on even more, Rose and Charlie are then captured by the Germans and sentenced to death as spies.
Rose then asks, as a last request, to be allowed to marry Charlie. Charlie, since he was out of liquor, had lost his boat, and figuring he was about to be executed anyway, agreed.
(I'm sure this made the "til death do you part" stuff much easier to promise)
But in between the wedding and the hanging, the German boat runs over the sunken boat, blows up and Rose and Charlie escape.
We are left to wonder what happened next. But I bet it involved a shave and a haircut.