Deep in the jungle of Central Vietnam lies the largest cave passage in the world — Hang Son Doong, a place of spectacular beauty. When a proposed cable-car system threatens to destroy the cave's ecosystem, the local community is divided over the benefits the development would bring. Beautifully shot and scored, "A Crack in the Mountain" is a powerful exposé about how the best of intentions could ultimately lead to one of the world's greatest natural wonders being trampled for money.