Until the middle of the 19th century, poor mountain farmers in Ticino sold their children to Milan as chimney sweeps. This is also the case for little Giorgio. He has to climb through dark chimneys and scrape off soot with his bare hands. But he doesn't give up: Together with his fellow sufferers, he founds the "Black Brothers". They stick together, fight back against their misery and get involved in fights with the Milanese street boys.