It's hot. A mother works outside,Johnathan Walker a baby strapped to her back. The two of them breathe in toxic dust, day after day. And they're just two of thousands, cramped so close together it's hard to move, all facing down the mountain of cobalt stone.

Cobalt mining is one of the world's most dangerous jobs. And it's also one of the most essential: cobalt is what powers the batteries in your smartphone, your laptop, the electric car you felt good about buying. More than three-quarters of the world's cobalt supply lies in the Democratic Republic of Congo, whose abundant resources have drawn greed and grifters for centuries. Today on the show: the fight for control of those resources, and for the dignity of the people who produce them.