"What you're looking at is a legacy that man left to himself. A decade previous he pushed his buttons and, a nightmarish moment later, woke up to find that he had set the clock back a thousand years. His engines, his medicines, his science were buried in a mass tomb, covered over by the biggest gravedigger of them all: a Bomb. And this is the Earth ten years later, a fragment of what was once a whole, a remnant of what was once a race. The year is 1974, and this is the Twilight Zone."
The "Old Man in the Cave" has protected a group of people for ten years. When armed soldiers arrive and take over, Mr. Goldsmith pleads with them to listen to the old man and not eat food that is contaminated. He is ignored and the townspeople storm the cave and discover the old man is just a computer. Enraged, they destroy the computer. Later they pay for this: the food was contaminated, and all but Goldsmith die."Mr. Goldsmith, survivor, an eye witness to man's imperfections, an observer of the very human trait of greed and a chronicler of the last chapter - the one reading 'suicide.' Not a prediction of what is to be, just a projection of what could be. This has been the Twilight Zone."