Kino, his wife, Juana, and their son, Coyotito, all live in a small hut by the ocean. They live happily together even though they don't have much. But then Coyotito is stung by a scorpion and they make a brave decision to see the doctor, only to be refused because they are poor.
As Coyotito grows more ill, Kino must continue his job: pearl diving. Juana puts seaweed on Coyotito's sting and then rows into the ocean with Kino to dive. Suddenly, luck hits them when Kino finds the Pearl of the World.
As Kino and Juana imagine their life with the money from The Pearl of the World, the doctor arrives. He insists that on treating Coyotito and although Kino is skeptical, he lets this happen. The baby soon gets sicker and then when the doctor returns and adds more medicine, starts to heal. Later that night, Juana and Kino hear a noise in the hut, something digging, and Kino strikes, drawing blood, but never finding out what the creature was.