The Tardis lands inside the sealed tomb of the Aztec High Priest Yetaxa. Barbara tries on a bracelet, and upon emerging from the tomb is hailed as Yetaxa's reincarnation. The Doctor, Ian and Susan become Yetaxa's servants. The tomb reseals itself behind them, blocking the travelers' return to the Tardis. Barbara hopes that as Yetaxa she can end the horror of human sacrifice, but the Doctor warns her that she cannot rewrite history. She tries anyway, finding a reluctant ally in the High Preiest of Knowledge, Autloc, and a deadly enemy in Tlotoxl, the High Priest of Sacrifice who doubts her divinity. Amid plots and counter plots, Ian is pitted against the Chosen Warrior Ixta, while the Doctor accidentally finds itself engaged to the lady Cameca and the Perfect Victim seeks to marry Susan. Now the four travelers must find a way back into the tomb before Tlotoxl finds a way th sacrifice all of them to his bloodthirsty god!