Filmmakers Kief Davidson and Richard Ladkani pan their cameras beneath the surface of Bolivia's Cerro Rico silver mines, a place so dark, depressing and frightening that locals believe it's the devil's home. Chronicling the daily ordeal of 14-year-old breadwinner Basilio Vargas -- who chews coca leaves on his way to work to numb his persistent, primordial terror -- this somber documentary captures the hellish realities of fear.