Following the death of Nasca, Empress Chimalma wants the blessing of the people for her upcoming marriage to Prince Heumac. Xipec, Governor of the Gold Region has come looking for slaves, and challenges the match. Otolmi the blind man suggests that Prince Heumac undertakes the perils of the Stone Cage to prove himself worthy of the title Emperor. Keelag, a mad recluse, is chosen to embalm the body of Nasca.

Having been miraculously resurrected by Keelag's magic potion, with her help Nasca devises a plot to strike the city with a plague of madness and help bring about the downfall of the Empress Chimalma. Prince Heumac and Tozo face tests of courage, wisdom, and ingenuity while trapped in the darkness of the Stone Cage. Chimalma has a vivid and scary dream.

Tozo and Heumac return from their tests, much to the delight of the Empress Chimalma. The Coronation of Chimalma and Heumac is announced, but it cannot take place until the missing crowns of Chichen-Itza are found. The task of finding them is down to Tozo. The statue of Tescata is pulled down, and in it's ruins Tozo finds the the mirror that holds the key to the hiding place of the missing crowns. Nasca though, wants it also. Keelag shows Nasca how to use magic powers to control the minds of all men.

Tozo is captured by Nasca and tortured by Xipec to try and find the whereabouts of the sacred mirror of Teshcata. Prince Heumac searches for him in vain. Nasca uses his magic lamp to mesmerize Chimalma and her councilors, making them think he is Otolmi, to exert his evil influence over them. Keelag poisons the first of the city wells. As the madness spreads, one of its victims is brought before Chimalma and the court.

Prince Heumac and his army make for immediate departure to rescue Tozo, who is still being tortured outside the city by Xipec. The forces of evil gather momentum, and Nasca tricks Chimalma into believing she is responsible for the madness and plague that has struck down the city. To atone, she must forfeit her life so he poisons Mataque to try and kill her.

After burying Chimalma alive, Nasca kills the old woman Keelag. Chimalma is rescued though, by Prince Heumac. Tozo discovers the secret of Teshcata's dark mirror and solves the mystery of the missing crowns of Chichen-Itza. Xipec challenges Heumac to a fight to the death in hand to hand combat. After Otolmi claims to be responsible for the madness, Chimalma, Heumac and the court of guards go to find and confront Nasca, but he hypnotizes them in one final desperate bid to seize power by pretending to be Teshcata. Only Otolmi sees through the facade.