10 years after a nuclear war took out most of the human race, a town relies on the mysterious Old Man in the Cave to tell them what food is or isn't safe to eat. Some military men from out of town arrive and begin spreading mistrust of the Old Man; a distinctly adversarial relationship develops between Major French (James Coburn), the chief military officer, and Mr. Goldsmith (John Anderson), 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 Tropes in the Cave:
- Adaptation Deviation: In the short story "The Old Man" by Henry Slesar, the war that destroyed civilization took place several generations earlier and scouting missions have determined that the residents of the Village are the last surviving humans on Earth. As such, humanity is rendered extinct very soon after the computer is destroyed. In the television adaptation, the war occurred only ten years earlier and there are numerous isolated pockets of humanity left in the United States.
- Adapted Out: In "The Old Man", the Village is run by the Governors. They are omitted from the television adaptation, in which Mr. Goldsmith is the settlement's leader.
- 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.
- Cargo Cult: Major French tells Mr. Goldsmith that there is a cult in what used to be Chicago that worships a statue made of fissionable lead as its god.
- 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".
- No Bikes in the Apocalypse: The residents of the Village use dilapidated cars drawn by horses.
- 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.
- Polluted Wasteland: In the aftermath of the nuclear war, large parts of Earth are contaminated with radiation. The Old Man tells Mr. Goldsmith that the Village should not plant tomatoes. When they ignored this advice, the tomatoes that grew looked like rotten watermelons because of the radiation. Jason also mentions freak carrots.
- The Reveal: The "Old Man" is a computer.
- Sole Survivor: Mr. Goldsmith, who didn't eat the radiation-infected food, is the only person who survives the episode.
- 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.
- You Are Already Dead: The people who eat the contaminated food. Even before anyone dies, Goldsmith calls French and his men killers.