The Doctor (Tom Baker) returns to the Time Lord home world on the eve of an invasion. Chaos ensues as Gallifrey turns into a battle ground and the Doctor assumes the presidency. Also notable for what happens to Lela. One of my favorite Episodes., Recommend to anyone who is a Doctor who fan.
The first half of this story will keep the viewer guessing, which is rare in Doctor Who. A pivital moment in the Doctor Who timeline, it is the first time we see the Time Lord homeworld, Gallifrey, invaded by an outside force. It is also a turning point for the Doctor himself, one of several that Tom Baker's Doctor would go through. In some ways, this is a follow-up to an earlier story "The Deadly Assassin", in that we see The Doctor's former teacher Berusa returning. We'll see him and the people here again in "The Five Doctors", as well. The radio series "Gallifrey" references this story a few times, as well. Definitely one of the best stories Tom Baker did as Doctor Who. It is, also, one of several instances where the Doctor becomes President of Gallifrey.