At the turn of the century, Nathan Walker comes to New York City to take the most dangerous job in the country. A sandhog, he burrows beneath the East River, digging the tunnel that will carry trains from Brooklyn to Manhattan. In the bowels of the riverbed, the sandhogs—black, white, Irish, Italian—dig together, the darkness erasing all differences. Above ground, though, the men keep their distance until a spectacular accident welds a bond between Walker and his fellow sandhogs that will both bless and curse three generations.