The season is notable for the departure of Sarah Jane Smith in The Hand of Fear and for The Deadly Assassin, a story set entirely on Gallifrey which expounded greatly upon the culture and history of the Time Lords, and the Eye of Harmony and Rassilon are mentioned for the first time. The Deadly Assassin also featured the return of the Decayed Master in a degenerated form and had the Doctor without a companion for an entire story for the first time in the history of Doctor Who. This story is also the first time the limit of regenerations is set.