10 years after a nuclear war took out most of the human race, a town confides in the mysterious Old Man in the Cave to tell them what food is and what isn't radioactive. Some military men from out of town arrive and begin spreading mistrust of the Old Man, particularly his habit of telling them to avoid eating certain food; a distinctly adversarial relationship develops between Major French, the chief military officer, and Mr. Goldsmith, the town's mayor. Eventually, French cracks some of the "tainted" food open, eats it, and doesn't immediately die; the townspeople have begun to turn against Goldsmith by now, and they demand to see the Old Man. Under threat of his life, Goldsmith allows them into the cave, where they find that the Old Man is a computer. Enraged at the deception, the townsfolk destroy the computer and return home to eat more of the "tainted" goods...
The next morning, the townsfolk and soldiers are all dead of radiation poisoning, as the food really was tainted. Goldsmith, the only survivor, sadly turns to leave the town.
The Old Man In The Cave contains examples of:
- After the End: The setting is post-nuclear war, with few survivors in even fewer towns remaining. The town in focus here is one of the largest around, according to the roving soldiers, with several dozen residents.
- An Aesop: About the importance of faith, giving the episode the feel of a post-apocalypse retelling of the Golden Calf.
- Apocalypse Anarchy: This episode deconstructs Living Is More Than Surviving by having Mr. Goldsmith's group devolving into this for the sake of "living" and destroying the thing that has kept them alive for so long (and would have kept them alive for far longer) just because they don't want to follow it anymore.
- Depopulation Bomb: According to Major French, between Buffalo, New York and Atlanta, Georgia, there are maybe 500 people alive — and this is a decade after the war.
- Downer Ending: Everyone but Mr. Goldsmith dies after they didn't listen to him, even worse the computer is destroyed so now there's no way to know what food is and isn't toxic.
- Living Is More Than Surviving: An example where this trope is used negatively, even a possible deconstruction; one of the townsfolk, in response to Goldsmith's protests that following the Old Man's instructions has kept them alive all this time, retorts that he wants to live, not just survive. He and every other person in the area except Goldsmith die by the end of the episode.
- Knight Templar: The soldiers that arrive and lead the destruction of the "Old Man".
- Only Sane Man: Mr. Goldsmith. He's the sole man amongst the survivors that understands destroying the only thing that can check what is and isn't irradiated will kill them all in short notice.
- Sole Survivor: Mr. Goldsmith, who didn't eat the radiation-infected food, is the only person who survives the episode.
- The Reveal: The "Old Man" is a computer.
- Too Dumb to Live: The townspeople eating food that could very well be poisoned just because they think there's a possibility it might not be.
- 20 Minutes into the Future: This episode takes place in a Polluted Wasteland in 1974.
- World War III: A nuclear war devastated Earth in 1964.