In the third book, Nina and her friends continue their fight against the evil magician Karkon and his minions. This time, in search of the Third Secret, the group travels to Mexico, where they must battle the mayor of Venice, LSL, who also turns out to be a Black Magician and takes the form of the Feathered Serpent. The main action takes place in Mexico, among the ruins of the Mayan pyramids. All the mayor's power and dark magic unleashes on Nina. The ancient Mayan god Yum-Ka comes to her aid. But the Feathered Serpent casts a spell on Nina.