Don't watch this video if you don't want the ending of Brother John spoiled. This 1970 movie features Sidney Poitier as a mystery man who comes to a small town full of xenophobic, vicious racist dickwads, all of whom believe that Poitier is something to do with local labor unrest or whatever.
And then, at the end of the film, we finally discover the weird truth about Poitier's Brother John.
So apparently, he's not from this world. And he represents a group of people who are concerned that the human race is an infestation of vermin, getting ready to jump off our world. First to the Moon, then to the stars and beyond. And they've sent Brother John to make an assessment — and it seems as though he's made his judgment. Will it be fire, ice, nuclear fallout, or something else? He won't answer. He just looks sorrowful and yet kind of pissed off, in that way that only Sidney Poitier really can. [Thanks to whichever commenter turned me onto this film!]