The song of evil comes into Kino’s head as the priest comes to help Coyotito.

Kino knows that his people were once "great makers of songs," and although there are no new songs, the songs remain and Kino knows them.

Coyotito, Kino’s baby boy, gets stung by a scorpion.

The music had gone out of Kino's head, but now, thinly, slowly, the melody of the morning, the music of evil, of the enemy, sounded, but it was faint and weak. (ch 3)

Kino’s hopes lie with the pearl.  With the pearl, he will have the ability to heal his baby.  Everyone is imagining how Kino’s pearl will benefit them.  No one cares about Kino, or the baby.

The doctor will only help them once Kino has the pearl, but Kino is reluctant to let the white doctor near his baby.  He has no other choice, and the baby becomes sicker.  Selling the pearl is more difficult than he imagined.  It is worth so much, it is effectively worth nothing.  He can find no one to trust.  The baby dies, and he returns the pearl to the ocean.