the throat, saying this is safety, this is warmth, this is theWhole.

The protagonist’s simple, contented life is suddenly altered forever when a scorpion makes its way down a rope hanging from a roof support and stings baby Coyotito. The effect of the traumatic event that Kino observes and is unable to prevent becomes the catalyst to his ultimate decline:

Kino’s breath whistled in his nostrils and he opened his mouth to stop it. And then the startled look was gone from him and the rigidity from his body. In his mind a new song had come, the Song of Evil, the music of the enemy, of any foe of the family, a savage, secret, dangerous melody, and underneath, the Song of the Family cried plaintively.

When the doctor refuses to travel to Kino and Juana’s brush house to treat the child, they rush Coyotito to the doctor’s home via a canoe. Upon arrival, the parents are turned away. The doctor will not properly care for the boy since the family is poor and cannot pay his fees. A servant tells them the doctor is out and unavailable.

Later that day, while Juana cares for the boy’s wound, Kino dives for oysters and finds a giant pearl. Immediately, his status in the community changes and friends and neighbors, the doctor who had rejected him and even the local priest take an interest in Kino’s intentions for his newfound wealth. Kino’s demeanor changes:

But Kino’s face shone with prophecy. My son will read and open books, and my son will write and will know writing. And my son will make numbers, and these things will make us free because he will know—he will know and through him we will know ... And suddenly he was afraid of his talking. His hand closed down over the pearl and cut the light away from it. Kino was afraid as a man is afraid who says, I will, without knowing.

The protagonist has been “transfigured” and is now committed to not sharing his good fortune. Greed has taken over his vision of life.

As Coyotito’s condition worsens, Juana views the pearl as an object of evil. She proposes getting rid of the jewel. After a violent attempt to steal the pearl is thwarted, Juana renews her plea to get rid of the evil object, but Kino’s obsession with it is too strong:

Kino, my husband, she cried, and his eyes stared passed her. Kino, can you hear me?

I hear you, he said dully.

Kino, this pearl is evil. Let us destroy it before it destroys us. Let us crush it between two stones. Let us—let us throw it back in the sea where it belongs. Kino, it is evil, it is evil!

No, he said. I will fight this thing. I will win over it. We will have our chance. His fist pounded the sleeping mat. No one shall take our good fortune from us, he said. His eyes softened then and he raised a gentle hand to Juana’s shoulder. Believe me, he said. I am a man. And his face grew crafty.

Juana makes a further attempt to get rid of the pearl, but Kino’s metamorphosis from a kind, gentle man is now complete. He assaults her and leaves her on the beach. On his way home, he is attacked by a group of men and kills one of them. He is now being tracked and seeks refuge at his brother’s home. When his own brother tries to convince him to get rid of the pearl, he continues to refuse and his obsession is complete:

I have it, said Kino, And I will keep it. I might have given it as a gift, but now it is my misfortune and my life and I will keep it ... Juan Tomas embraced his brother with the double embrace and kissed him on both cheeks. Go with God, he said, and it was like a death.

You will not give up the pearl?

This pearl has become my soul, said Kino. If I give it up I shall lose my soul.

Kino’s character had changed and it cost him his soul, his relationships, and his son. He was left with only the memories of his greedy obsession.

Kino and Juana are spiritual and superstitious. This novella opens by saying it is a parable about dualities, particularly between good and evil. Kino thinks of things in terms of songs: the pleasant Song of the Family and the foreboding Song of Evil, characterized first by the scorpion. When the scorpion approaches the baby, Juana tries using ancient and religious prayers: 

Under her breath Juana repeated an ancient magic to guard against such evil, and on top of that she muttered a Hail Mary between clenched teeth. (Chapter 1) 

Although Kino is a man of action, Juana is also assertive and strong. She lives simply but does not necessarily limit herself to the role of a subservient wife: 

She, who was obedient and respectful and cheerful and patient, could bear physical pain with hardly a cry. She could stand fatigue and hunger almost better than Kino himself. In the canoe she was like a strong man. (Chapter 1) 

She is also the one who suggests going to the doctor since he will not come to them. Juana shows more wisdom and intuition than Kino. She realizes the pearl will bring nothing but trouble. Kino is convinced otherwise and resorts to striking her when she tries to get rid of it. 

Kino loves his family and is devoted and determined but he is also stubborn. Juana is the voice of reason in their family. When Kino says "I'm a man" to Juana,

It meant that Kino would drive his strength against a mountain and plunge his strength against the sea. Juana, in her woman's soul, knew that the mountain would stand while the man broke himself; that the sea would surge while the man drowned in it. And yet it was this thing that made him a man, half insane and half god, and Juana had need of a man; she could not live without a man. (Chapter 5) 

But Juana could also command authority with her own reason and womanhood, and override Kino's stubborn determination: 

Sometimes the quality of woman, the reason, the caution, the sense of preservation, could cut through Kino's manness and save them. (Chapter 5) 

Kino and Juana are dedicated to each other from the start. But by the end of the novella, despite their tragedy or maybe because of it, they were more like equals than before: 

The two came from the rutted country road into the city, and they were not walking in single file, Kino ahead and Juana behind, as usual, but side by side.