Kino is a young indigenous fisherman who lives with his wife Juana & infant son Coyotito in La Paz. The baby gets stung by a scorpion. The parents take Coyotito to the racist doctor in the city, who refuses to treat the baby.
Juana prays Kino finds a pearl to pay the doctor. Coyotito seems to have recovered due to his mothers simple free remedy. Kino finds the greatest pearl in the world.
News of Kino's pearl reaches everywhere, arousing desire and greed but Kino believes the pearl will free them all by allowing Coyotito to get an education. The doctor comes to them and treats the baby but Kino's suspicious that the treatment is a hoax. Kino buries the pearl and is awakened to fight off a would-be robber, then Juana begs him to throw away the evil pearl.