Doctor Who/Recap/S18/E04 State of Decay

"The Doctor: Do you know, it just occurs to me. There are vampire legends on almost every inhabited planet. Romana: Really? The Doctor: Yes. Creatures that stalk in the night and feast on the blood of the living. Creatures that fear sunlight and running water and certain herbs. Creatures that are so strong they can only be killed by beheading, or a stake through the heart."

The TARDIS (still in E-Space) lands on a planet that seems to be inhabited only by a single small village full of peasants and a castle occupied by three sinister rulers. This turns out to be because the planet's inhabitants come from a crashed spaceship from Earth; the castle is built from the remains of the spaceship. The captain and his executive officers became the rulers, and the peasants are descended from everybody else.

That's not the interesting bit, though: the interesting bit is that the Three Who Rule are vampires. And they're working to revive their master, a Giant Vampire who fought (and nearly defeated) the Time Lords themselves aeons ago.

The Doctor must answer the question: Just how do you deal with a Giant Vampire? A bit of wood with a point at one end really isn't going to do the job...

Terrance Dicks had originally proposed this story several years earlier, for the slot that ended up going to "Horror of Fang Rock"; it was turned down at the time because the BBC was about to air a big-budget adaptation of Dracula, and they didn't want anybody to think Doctor Who was taking the mickey.

Tropes
"Aukon: The guards must hold the tower to the last man. Guard: We are outnumbered. Unless you aid us we shall all be killed! Aukon: Then die. That is the purpose of guards."
 * Alien Blood: The Doctor's blood is blue, though in all other episodes before and since it's been red.
 * Aristocrats Are Evil
 * Exposition of Immortality: Photos of the Three Who Rule are found by the Doctor in the databanks of the rebel's computer, confirming his suspicions that there's something not quite right and that they've been around for millenia.
 * Fake Defector: After spending a couple episodes under mind control, Adric pretends to side with the Three Who Rule so he can safely wait for an opening to save Romana. This plan does not work, but at least he apologizes.
 * Feudal Future
 * The Guards Must Be Crazy
 * Impaled with Extreme Prejudice: The Doctor stabs the Giant Vampire through the heart with a rocketship.
 * Looks Like Cesare: The Three.
 * Medieval Stasis: Enforced by the Three Who Rule
 * The Necrocracy
 * No Immortal Inertia
 * Ooh, Me Accent's Slipping: "And certain 'erbs". Baker slips out of his BBC English accent for a second.
 * Our Vampires Are Different: The Three Who Rule are pretty standard Hammer Horror vampires, but the gigantic ur-Vampire certainly qualifies as Different.
 * Percussive Maintenance
 * La Résistance
 * Special Effects Failure: The "Giant Vampire"? A hand in a weird glove randomly grasping at the air for about four minutes. The rocket that supposedly stakes it can also count, and strangely apparently manages to stake it by landing right next to its wrist.
 * Supernatural Elite: The Three Who Rule are vampires, feeding off the peasants whom they rule.
 * Title Drop
 * Torches and Pitchforks
 * Uberwald
 * Vampire Monarch: The head vampire is an Eldritch Abomination. Once the doctor stakes it with a rocket ship, the other (human) vampires crumble to dust.
 * We Have Reserves: Aukon's attitute to his guards.