Doctor Who/Recap/S30/E03 Planet of the Ood

"Donna: It's weird, but... being with you, I can't tell what's right and what's wrong anymore.

Doctor: It's better that way. People who know for certain tend to be like Mr. Halpen."

The Doctor and Donna land on a gorgeous snowy world -- your favourite alpine vistas, cranked up to 11--somewhere in the distant future. It is the Oodsphere, home planet of the Ood, the apparently willing slave race we first met in "The Impossible Planet"/"The Satan Pit".

All is not well on the Oodsphere. Ood Operations, the Ood suppliers to the galaxy, are sitting on a disturbing fact: Ood everywhere have been going berserk and killing their masters. The only symptom is that the Ood's eyes will turn red just before it snaps.

The Doctor and Donna sneak off to interview some Ood, but the only hint the Ood themselves can give is that "the circle must be broken". The Doctor and Donna discover, to their horror and disgust, that the process that wild Ood undergo to turn them into slave Oods is... lobotomy. The communication orb isn't just an addition to their bodies: it's a replacement for their second, external brain. The Doctor gently connects to Donna telepathically and makes her hear the collective mind-song of those Ood that are still intact.

But even the unaltered Ood are being restrained somehow -- something is holding back their song. That's when they come across the third brain of the collective Ood consciousness, a giant mass imprisoned in a ring of machinery and electricity -- the circle that must be broken.

They save the Ood, hear their Song Of Freedom, and receive in return a cryptic message about the Doctor's song ending soon.

Tropes

 * Batman Gambit:
 * Body Horror: Halpen's "hair formula".
 * Chekhov's Gun: The drinks Mr. Halpen keeps knocking back are blatantly going to bite him somehow. Boy, do they ever.
 * Corrupt Corporate Executive
 * Continuity Nod: Oodsphere being in the same system as Sensphere, homeworld of the Sensorites.
 * Fandom Nod: To the idea that the Ood are related to the Sensorites.
 * The Doctor is all gleeful to walk out and find a snowstorm of actual snow. (The last few times it's been, respectively, the ashes of a Sycorax spaceship, bits of Racnoss web and artificial snow expelled by the TARDIS, and ballast dropped by a damaged interstellar cruise liner)
 * Distressed Dude: The Doctor tied to a pole.
 * Fan Service: David Tennant tied to a pole? With handcuffs?
 * Fantastic Racism: Emphasized by the fact that the whip-happy slave overseer is a black guy, and the PR representative that is tasked with justifying slavery to the audience is Indian.
 * Foreshadowing:
 * Happiness in Slavery: Subverted after being set up way back in "The Impossible Planet."
 * Hoist By His Own Petard: The overseer who tries to gas the Ood winds up being the only victim of the gas.
 * Ignored Epiphany
 * Improperly Placed Firearms: Guards with M4s and a guy with a PPK; in the 42nd Century. Though it is currently believed that small arms have hit a peak where making them any more powerful would make them uncontrollable.
 * Karmic Transformation:
 * Long Speech Tea Time: Donna's first impression of the Oodsphere is that it's bloody freezing. The Doctor encourages her be more awestruck by the setting, consider how last week she was in Chiswick was getting up, working, coming home, watching telly and going to bed and now she's travelling across space and time to land on alien worlds...and finds she's gone back into the TARDIS to get a coat.
 * Never Trust a Hair Tonic: Mr. Halpen's hair tonic... isn't.
 * Planet of Hats: a factory that builds hats specifically.
 * Railing Kill: When Dr Ryder reveals he's a Friend of the Ood, Halpen pushes him over the rail and into the Ood brain.
 * Red Eyes Take Warning
 * Retro Rocket: Of a similar design to the one from the last Ood episode. Donna approves ("You've got a box, he's got a Ferrari!")
 * She Is Not My Girlfriend: "Pleased to meet you, Doctor Noble, Mrs. Noble."
 * Shout Out: The "comedy classic" Ood is programmed to say "D'oh!" when it drops something.
 * We Will Use Manual Labor in The Future
 * The X of Y
 * Zerg Rush: A perpetual favorite of berserk Ood.

There's a better / home a-waitin' / In the sky, Lord, in the sky