Aired May 23 - June 13, 1964
Episode 1 – The
Episode 2 – The Warriors of Death
Episode 3 – The Bride of Sacrifice
Episode 4 – The Day of Darkness
Written by John Lucarotti
Directed by John Crockett
Autloc proclaims Barabara to be the reincarnation of their god, though Tlotoxl, High Priest of Sacrifice, has his doubts. In order to keep her friends safe, Barbara plays along. Susan is allowed to remain with her as her handmaiden, while Ian is chosen to lead the Aztec army as her representative, which creates a dangerous enemy out of Ixta, the previous leader. The Doctor meanwhile, is sent to the Garden of Peace with the other Aztec elders, where he begins a flirtation with a wise woman named Cameca, partly in order to discover a way back into the tomb.
Barabara, who specialized in Aztec history when training as a teacher, has an ulterior motive. Believing that the Aztec practice of human sacrifice is what doomed their society, sets about trying to change history by ending the practice. This immediately puts her at odds with Tlotoxl, who begins plotting her downfall, as well as the Doctor, who passionately tries to persuade her of the folly of changing established history.
During the solar eclipse at which the Perfect Victim's sacrifice is due to take place, Ian and Ixta fight on the roof of the temple, where Ixta falls to his death in the streets below. Meanwhile, the Doctor has constructed a pulley system to open the door and uses it to gain access to the TARDIS. The Doctor and Cameca part, with Cameca giving him a seal to remember her by. And Tlotoxl resumes the acts of sacrifice.
Barbara and the Doctor reconcile their earlier argument, with Barbara heartbroken that she couldn’t save the Aztec society. But, in convincing Autloc of the barbarity of human sacrifice, the Doctor tells her that she did make an improvement in the life of one man. And that is something. The TARDIS crew go on their way, the Doctor remembering to bring Cameca's seal with him.