Esperanza Quintero (Rosaura Revueltas) is a miner's wife in Zinc Town, New Mexico, a community which is essentially run and owned by Delaware Zinc Inc. Esperanza is thirty-five years old, pregnant with her third child and emotionally dominated by her husband, Ramon Quintero (Juan Chacón). The majority of the miners are Mexican-Americans and want decent working conditions equal to those of white, or "Anglo" miners. The unionized workers go on strike, but the company refuses to negotiate and the impasse continues for months. Esperanza gives birth and, simultaneously, Ramon is beaten by police and jailed on bogus assault charges following an altercation with a union worker who betrayed his fellows.