The Twilight Zone - The Old Man In The Cave

Ten years after an atomic apocalypse, a small group of survivors manage to eke out a very difficult existence. They've managed to survive in large part due to the advice they receive from an old man who lives in a cave outside of the town. Goldsmith acts as the intermediary and the old man's advice on things like crops or the safety of a batch of old canned goods are usually correct. When four soldiers led by Major French arrive in the town, the social order is upended with the townsfolk attacking the old man's cave but not really prepared for what they find inside.