The Doctors embark on their greatest adventure across space and time in this 50th Anniversary Special.

The Doctor, Romana, K9 and Adric - an Outler from Alzarius who has stowed away aboard the TARDIS - arrive on a planet where the native villagers live in fear of 'the Wasting' and of three Lords named Zargo, Camilla and Aukon who rule from an imposing Tower. The Lords are soon revealed to be vampire servants of the last of the Great Vampires, a race referred to in Time Lord mythology.

The Doctor and Romana receive a distress signal and arrive on Chloris, a lush and verdant world that has only small quantities of metals, all of which are controlled by its ruler, Lady Adrasta. Adrasta keeps order with the aid of her Huntsman and his wolfweeds - mobile balls of vegetation - while a band of scruffy thieves, led by Torvin, organize raids on her palace to steal whatever metal they can.

The Doctor and Grendel engage in a duel of wits with a kingdom hanging in the balance.

Only a last-minute rescue can save Romana, the fourth segment and the kingdom from Grendel's infamy.

Clara is alone in Victorian London with a man she doesn't know, a dinosaur in the Thames, and a spate of deadly spontaneous combustions. The Doctor has changed. It's time you knew him.