I'm trying to remember these details from 20+ years ago, so I really have no good recollection of where I encountered this story. I'm pretty sure it was a TV show, but I'm not certain of that.
A young boy lives in a small camp that is surrounded/encased in some type of barrier or wall. He, like all young children in the camp, is told that many years ago there was some disaster that destroyed much of the world, and that the barrier/wall is the only thing that keeps their small camp habitable. No one is allowed to cross the barrier and leave the camp. The young boy's curiosity builds up during the story and, at the end, he decides to cross the barrier. As soon as he does, the camp behind him and all the people vanish and he finds himself in some type of cage in an alien-looking landscape. On the cage is a sign (which we are somehow able to understand) that reads: "Homo Sapiens, last of species".
Anyone have a title and what series this was from?