A gold mine at Perko, Burkina Faso. Opio is thirteen years old and works on the surface, his only salary a sack of stones every month. His father wants him to get some professional training, but he cannot pay the tuition fees. Opio must come up with this money and asks his boss for a promotion: the right to go down into the subterranean mine shafts where, it is said, men can become rich.