The Doctor returns to Gallifrey to claim the presidency. Borusa has been taking care of the Time Lords since the Doctor wasted Goth in The Deadly Assassin of Death but under Gallifreyan law, the Doctor's request cannot be refused. So Four becomes Lord President of Gallifrey and starts behaving strangely. He has Leela banished and is seemingly plotting to allow Gallifrey to be invaded by the evil Vardans. Oh shit nigga.