STORYLINE
In the fifteenth century civilization is hardly civilized, as the Doctor discovers when the TARDIS materializes in an ancient Aztec temple.
When Barbara is mistaken for the reincarnation of the Aztec's High Priest, Yetaxa, she seizes the opportunity to put an end to the ceremonial rites of human sacrifice and save the Aztecs from self-destruction.
The Doctor must somehow convince Barbara to let history follow its natural course and return to the TARDIS before their real identities are discovered. Can they escape before they become the next blood sacrifices?