If slavery were an American state it would have the population of California and the economic output of the District of Columbia, but it would be the world’s third-largest producer of CO2.

We think of Steve Jobs in his black turtleneck as the origin of our iPhones, or imagine a local funeral director carving a loved one’s name into a tombstone. Whether we are grilling shrimp for our friends or buying T-shirts for our children we generally think of these things as beginning where we first encountered them, at the shop, at the mall, in the grocery store. But just as each of us is deeper than our surface, just as each of us has a story to tell, so do the tools and toys and food and rings and phones that tie us together.

Back in Germany the filmmakers quizzed the businessmen that sold the tombstones; these men were appalled when they saw footage from the quarries.

Slavery is a great way to keep your costs down, but there’s another reason why that granite is so cheap—the quarries themselves are illegal, paying no mining permits or taxes. The protected state and national forest parks rest on top of granite deposits, and a bribe here and there means local police and forest rangers turn a blind eye.

Slavery in granite quarries is a family affair enforced by a tricky scheme based on debt. When a poor family comes looking for work, the quarry bosses are ready to help with an “advance” on wages to help the family settle in. The rice and beans they eat, the scrap stones they use to build a hut on the side of the quarry, the hammers and crowbars they need to do their work, all of it is provided by the boss and added to the family’s debt. Just when the family feels they may have finally found some security, they are being locked into hereditary slavery.