Doctor Who/Recap/S14/E04 The Face of Evil

"Leela: "The Evil One!" The Doctor: "Well, nobody's perfect, but that's overstating it a little.""

The TARDIS arrives on a planet where the primitive native tribe known as the Sevateem identify him as "The Evil One", and worship a god called Xoanon. A young female warrior called Leela shows the Doctor the image of the Evil One - his own face carved into the side of a mountain.

The Doctor investigates and discovers that Xoanon is really a ship's computer that he tried to repair at some point in the past and ended up driving it mad and giving it split personalities. Xoanon is tended by another tribe - the Tesh, who live in the crashed spaceship and operate as a Cargo Cult while continuing to value intelligence and mental power over courage and physical power like the Sevateem. The Doctor theorises that the Sevateem are descended from the ship's Survey Team, and the Tesh from the Techs.

The Doctor and Leela manage to access Xoanon's memory banks, after running the gauntlet of traps and mazes set both by the Tesh and Xoanon himself, and erase the multiple personalities, leaving the computer sane once more. As the Doctor prepares to leave, Leela pushes on board and announces she is joining him in his travels...

Tropes
"The Doctor: "Would you like a jelly baby?" Leela: "It's true, then. They say the Evil One eats babies.""
 * Action Girl/Nubile Savage: Leela. Oh yes.
 * AI Is a Crapshoot: Played with - the computer is mad, but it's entirely the Doctor's fault, and it ends with his restoring its sanity rather than blowing it up.
 * Attack! Attack! Attack!: The Sevateem under both Andor and Calib.
 * Cargo Cult: Both the Tesh and the Sevateem, to different extents. Played with a bit in that they're worshiping their own technology, just from a different point in time.
 * Deus Est Machina
 * Don't Touch It, You Idiot!: The last words we hear are the Doctor shouting at Leela not to touch that button after she's slipped inside the TARDIS...
 * Eats Babies: spoofed


 * Evilutionary Biologist: All of the characters are victims of a eugenics experiment being run by Xoanon. By and large, they bear him no hard feelings for it afterwards.
 * Heel Face Turn: Neeva and Calib.
 * Heroic Sacrifice: Neeva, not entirely intentionally.
 * Human Shield: Done by the Doctor of all people. When confronted by the savage Sevateem tribe, the Doctor threatens to kill one of them "with this deadly jelly baby" if they don't back off. The Sevateem surprise the Doctor by responding, "Go ahead, kill him." Determined not to be upstaged, the Doctor simply eats the jelly baby instead. "I don't take orders from anyone. Take Me to Your Leader."
 * Invisible Monsters: Deconstructed. The Doctor works out that they can't see, since light would just pass through any eyes they had, and must rely on other senses. This lets him distract them with an alarm clock long enough for him and Leela to get to safety.
 * Jumped At the Call: Leela
 * Lost Colony
 * Nice Job Breaking It, Hero
 * Noble Savage: All of the Sevateem, but Leela in particular.
 * Pay Evil Unto Evil: The Doctor kicking a vicious Horda onto the back of a Sevateem man who smacked Leela in the face.
 * Piranha Problem: The Test of the Horda is a land-dwelling version.
 * Please Kill Me If It Satisfies You: After Xoanon is healed, it makes this offer to the humans via the Doctor.
 * Romanticism Versus Enlightenment: The Sevateem versus the Tesh.
 * Satan Is Good: From the Sevateem's point of view. Also, Leela is pretty quick to team up with the Doctor when she still thinks he's the "Evil One".
 * Shoot the Rope: The Sevateem give the Doctor a Trial By Ordeal which consists of this.
 * Strapped to An Operating Table: Leela and the Doctor, by the Tesh.
 * Stripperiffic: The Sevateem dress sense, male and female.
 * Take Me to Your Leader
 * The X of Y
 * Walking Shirtless Scene: All the male Sevateem.