Doctor Who (1963) Season 18 Episode 8 Meglos (4)

The Doctor and Romana find themselves on the desert planet of Tigella, where the two factions of a civilization are at odds over whether or not to reactivate a powerful energy source. The Doctor is approached by a group of religious zealots who believe that the energy source is actually a god named Meglos. However, the Doctor discovers that Meglos is actually a sentient cactus-like creature who plans to use the energy source to take control of the universe. To stop Meglos, the Doctor must team up with the Tigellans and his archenemy the Master.