Doctor Who/Recap/S15/E05 Underworld

"The Quest is the Quest!"

- Various Minyans

The TARDIS lands on a spaceship, the R1C, commanded by a man named Jackson. He and his Minyan crew are on a quest to recover their "race banks" from another ship, the P7E, which left centuries ago to form a new colony. The R1C is buried by a meteor storm but the Doctor helps them escape - before they crash into a small planet just as the serial's budget runs out.

Investigating the planet, the Doctor finds a system of caves that leads to the P7E, long ago buried by asteroids. The P7E's computer, Oracle, has gone insane and rules over the survivors of the Minyan crew with the aid of the robotic Seers. It allows Jackson to take the race banks, but the Doctor realises that they are just fakes, primed with fission grenades. The Doctor tricks Oracle into allowing him to take the real race banks, meanwhile returning the fakes via the Seers. The resulting explosion destroys the P7E and propels the R1C off on its voyage to Minyos II with the P7E's survivors.

Tropes
"The Doctor: What is blown can be sucked."
 * AI Is a Crapshoot
 * Beneath the Earth: The reason for the episode's title, rather than, well, The Underworld.
 * Cargo Cult
 * Cold Blooded Torture
 * Deadly Gas: Used to "fumigate" an area of tunnel where a dissident is thought to be hiding.
 * Death Is Cheap: Each of the Minyans has regenerated thousands of times.
 * A God Am I
 * God Is Evil: This is how the Minyans view their Gods, at least. And the Time Lords are their Gods...
 * Graceful Loser: After having spent the previous episode chewing on the scenery, the Oracle resigns itself to destruction with surprising dignity.
 * Gravity Sucks: Played straight and then inverted when it is the R1C itself that is exerting too much gravitational force on its surroundings, sucking in smaller objects and becoming the core of a new planet.
 * Heroic Sacrifice: Attempted by Herrick, but the Seers refuse to kill him.
 * Human Sacrifice
 * I Want My Nubile Savage Back: The Doctor isn't happy when Leela is momentarily converted into a nice person.
 * Kick Them While They Are Down
 * Made a Slave
 * Negative Space Wedgie: the spiral nebula at the beginning of the episode.
 * Oh Crap: "Two-thousand megatons?!"
 * One Word Title
 * The Quest
 * Really 700 Years Old: Each of the Minyans is about 100,000 years old.
 * Reverse the Polarity: Justified in dealing with the Deadly Gas:


 * Sarcastic Confession: The Doctor goes back to the planet to get rid of the fake race banks, which are actually bombs. He travels all the way back to where he can get captured again (rather than just leaving them on the surface) so it's obvious that he planned to have them taken from him, yet when forced to give them up, he explains that they are really bombs. "You can do better than that..." replies a villain and confiscates them. The bombs blow up the planet, of course.
 * Troubled Production: The story (and the one that followed) suffered from The BBC slashing the rest of the season's budget due to the economic crisis the UK was suffering, leaving them with barely enough money to build the spaceship set, and nothing to build sets of the caves, or to shoot them on location. As a result, they ended up having to resort to filming all the non-spaceship scenes on a bluescreen, and matte the actors into miniature cave sets.
 * Whole Plot Reference: to the quest for the Golden Fleece.