The crew venture out of the Tardis into 15th Century Mexico and the tomb of the Aztec High Priest Yetaxa. When Barbara stumbles upon the Aztecs they mistake her for a reincarnation of the High Priest himself.

Barbara's interference in the Aztec practice of human sacrifice casts doubt over her supposed divinity and puts the whole crew in jeopardy.

It is the day of the solar eclipse when Susan is to be punished for her refusal to marry. The Doctor and his companions try to escape before they are sacrificed to the Sun God.

The Doctor is called in to investigate a pair of mysterious seed pods in the Antarctic. As the Doctor looks to uncover their mysteries, a ruthless collector arrives to add the seeds to his menagerie. Things take a turn when it is discovered that the pods harbor intelligent life with sinister plans of its own.

The Doctor is called in to investigate a pair of mysterious seed pods in the Antarctic. As the Doctor looks to uncover their mysteries, a ruthless collector arrives to add the seeds to his menagerie. Things take a turn when it is discovered that the pods harbor intelligent life with sinister plans of its own.

The Doctor looks for a means of stopping the Master's plan to destroy the Earth's greatest minds.

The Doctor tampers with the Rani's TARDIS.

The Doctors alarmed seeing coverage of an archaeological dig into an ancient barrow near the village of Devil's End.