Tom Baker
State Of Decay

Trying to find a way out of E-space the TARDIS materialises on an unknown planet where the inhabitants are ruled by the Lords, otherwise referred to as the Three Who Rule.

The natives appear to be primitive, and the Doctor learns that the Lords have outlawed all technology and knowledge, although there are some rebel factions.

Overlooking the settlement is a great tower which houses the Lords. The Doctor learns that the Lords are in fact from Earth, brought to the planet by the Great One. The tower is in fact the spacecraft in which they arrived.

The Great One is in fact a vampire, the survivor of a war with the Time Lords. The Lords have been converted to vampires and feed of the natives.

The Doctor manages to destroy the Great One by using the spacecraft to go into orbit, and come straight down into the Great One's heart. With the Great One dead the Lords die also.