John Steinbeck's 1947 novella is a kind of parable about how the things we think we want desperately can actually sometimes destroy our lives when they come to pass. Steinbeck introduces us to a young family of indigenous Mexicans who make a living pearling. Kino, his wife Juana, and their baby son Coyotito live in a poor village on the edge of a fairly prosperous town called La Paz. Their lives are simple, and poor, but in the opening of the pages the family seems extremely content with their lives. However, things change when Coyotito is stung by a scorpion in a freak accident, and the extent of the deprivation they suffer from being poor, uneducated, and indigenous becomes obvious.

Because of their son's size Juana and Kino are terrified that he might succumb to the scorpion sting without medical intervention. Juana desperately screams for someone to fetch the doctor, but Kino and the other residents point out that the doctor has never come to the village, and even if someone attempted to ask him to come, he would not. Juana decides that if the doctor will not come to Coyotito, she and her husband will have to take their son to the doctor. They take with them everything they have of value: eight small misshapen seed pearls. The doctor is unimpressed, and pretends to be called out on an emergency.

In hopes that they might find a pearl worthy of the doctor's attention, Kino and Juana immediately begin searching for a better pearl. While Juana prays in the canoe, Kino dives for oysters. Eventually, he finds one that is set apart from the rest, it is larger, and cleaner than the other oysters, and for some reason Kino has a good feeling about what might be inside. What he and Juana find are outside of their wildest expectations. It is a pearl bigger than anything ever found in the area.

Word about Kino's pearl spreads very quickly. Everyone in the town, everyone in the village, even complete strangers, start to imagine how they themselves could benefit from Kino's good fortune. Before long the town Priest visits the little village, something he never does, specifically to subtly pressure Kino to donate heavily to the church. Kino has his own plans for the money though, specifically; he hopes to give his son, Coyotito a good education. He would also like to officially marry his wife in a church. He would like to buy a rifle. His desires are quite modest, given his gains.

Others in La Paz have more sinister ideas. The doctor who refused to treat Coyotito only the day before arrives. He does not mention that he has heard anything about the pearl, he says only that he heard that they have a baby who was stung by a scorpion. When Kino tells him that his son is nearly back to normal, the doctor lies to them and says that the baby could still be deathly ill. Not knowing any better, Kino allows the doctor to "treat" his child. The doctor administers a white powder to the baby as a "cure", but Coyotito soon begins to go down hill. The doctor is able to miraculously "cure" the baby and asks for payment. He is no doubt hoping that the family is naïve enough to simply hand the pearl over, but Kino tells him that he will pay him once he sells it.

That night an intruder comes to the brush house, Kino attempts to fight him off, and succeeds, but is also left bloodied and injured. His wife, Juana, is terribly distressed by this turn of events, and she suggests that they get rid of the pearl right away. Kino insists that they sell the pearl the next day, reluctantly she agrees. The next day Kino attempts to sell the pearl in La Paz, but he is given low-ball offers because, according to the local buyers the pearl is so large that it holds no appeal for jewelry. Kino is infuriated, and vows to go to the capital the next day and sell the pearl there. Kino returns home and buries the pearl. Again, Juana suggests that they rid themselves of the pearl, and again Kino attempts to reassure her.

In the middle of the night, though, Juana removes the pearl from its hiding place. As she does Kino wakes and sees her. She runs through the door, and he follows her down to the ocean. As she is about to hurl the pearl in, he catches her, and beats her mercilessly. He leaves her there, and attempts to go back home, but during his walk he is attacked by a group of men. He is able to kill one, and the rest flee, but he is badly hurt, and has dropped the pearl.

When Juana is able to collect herself from her assault she takes the same path as Kino did back to the house. First, she finds the pearl, and then notices Kino and the dead man. In an effort to save her family, she convinces Kino that they must flee immediately. She drags the corpse into the bushes, and agrees to go get Coyotito while Kino prepares the canoe. When Kino arrives at the shore he finds that his canoe has been destroyed, so he goes back to his house. As he approaches he sees that his house is on fire. He meets up with Juana and Coyotito who are both fine, and hides in his brother's house. Kino's brother Juan, and his wife Apolonia are happy that the family did not parish in the fire, and agree to house them for the night and mislead the rest of the village about what may have happened to them.

That night the family takes the pearl, and leave for the capital. They avoid town, and head north, walking until the sun rises. They are able to sleep for most of the day, but then Kino notices that three trackers have followed them. Kino is able to throw them off briefly, and the spend most of the day walking up a desert mountain with no water. Eventually, they find a water source, and a cave, and Kino decides to attempt to throw the trackers off again. His plan is to hide his wife and child in the cave, while he creates a false trail.

The plan is foiled, however, when the trackers decide to make camp at the water source, very close to the cave in which Juana is hiding with a very young child. Juana and Kino both understand that it is only a matter of time until Coyotito reveals their presence. Kino decides that he must act preemptively, and kill the men before they notice them. Just as Kino is about to strike, Coyotito makes a little noise. One man speculates that it's a coyote, and shoots into the darkness to scare it off. As he pulls the trigger Kino attacks him, slitting his throat. He then grabs the gun, and hits one of the other trackers with it, finally, he shoots and kills the last one. Kino's triumph is very short lived though, because as soon as the last man is dead he notices Juana's wails. The tracker's shot had killed Coyotito.

Scared forever the family return to their village. They walk silently through town and down to the ocean, when they reach it, they throw the pearl back in.