Doctor Who/Recap/S29/E03 Gridlock

The Doctor tells Martha that her one trip is over, and she can go home now... unless she wants to travel more. No reason, really, he'd just like to travel more. In fact, he'd like to take her to the future: New New New, etc., York. Where drugs are cheap, legal, and socially acceptable. Where people inexplicably look like cats. Where traffic never moves. Where the Doctor also took Rose once.

The Doctor even tries to make the same little jokes he made to Rose when he first took her there, but they just don't work as well when Rose isn't around to hear them. By now, Martha's figured out that she's the Doctor's "rebound", and she doesn't like it one bit. Also, the TARDIS has taken them to the undercity slums, where things aren't quite as happy as they are above the smog.

Martha gets kidnapped by the ghost chick from Being Human so that her kidnappers can have enough people in the car to get access to the elusive carpool lane. The Doctor chases after her... into the Traffic Jam From Hell.

Before he dies of extreme toxic smoke inhalation, though, he gets picked up by Catfolk Thomas Kinkaide Brannigan (who looks like Father Dougal as a cat-person) and his wife Valerie. Estimated time of arrival? Oh, another six years or so.

Screw that. The Doctor jumps from car to car, and tries climbing down to Martha's spot, but he can only get so far.

Meanwhile, giant evil crabs that feed off pollution have snatched Martha's car out of the air and are hell-bent on eating her. The Doctor quickly recognises them from an old Missing Episode and notes that they've devolved into mindless beasts over time, living in the depths of the expressway. Even if he could get there, there's hardly any way to get back.

The Doctor will not be deterred. He gets into the upper city, where the only remaining "people" are an elderly cat nun and the Face of Boe, the oldest being in the galaxy, who is the only thing powering the expressway and keeping the rest of demi-humanity alive. It turns out that the planet's inhabitants all got addicted to the drugs, causing them to waste away in drugged-out bliss... and then the drugs produced an unstoppable plague that killed everyone (including itself). And all the expressways are closed, and have been closed for years. All those cars with all their eternal fuel and food supplies are driving in eternal circles around the deadly city smog.

The quarantine placed on the planet was set to last 100 years, so it has to be released manually. The Face gives his life to open up the expressway exits and save Martha. The Doctor opens the gates of... well, Heaven, and all the cars ascend into the bright upper city, with the people inside praising Jehova for saving them from the crabs of... well, Hell. They sing hymns and everything. This planet really sets off the Doctor's messianic side, after that whole "getting baptised by nuns with a panacea and curing all the lepers with a single touch" thing he did last time.

As Face dies, he imparts his final message, as foreshadowed in "New Earth". The message? "You are not alone."

Martha refuses to leave until the Doctor tells her just what he is and what's going on. The Doctor sits down with her and tells his story from the beginning, starting with "there was a war"...

Tropes
"Brannigan: This Martha...she must mean a lot to you.
 * Aliens of London: Despite being New New York, every person you see (except Brannigan and the news anchor) is very much British due to the TARDIS' Translation Convention.
 * Always Save the Girl:

The Doctor: Hardly know her."


 * The Atoner: The elderly cat nun attendant was the youngest cat nun villain in New Earth.
 * Big Word Shout: MAAAAAAAARTHAAAAAAAAAAAA!
 * Call Back: The Macra. From a Missing Episode no less.
 * The City Narrows: The other side of New New York.
 * Cute Kitten: Most likely the reason for an anthropomorphic cat and a demi-human woman having a litter of seemingly ordinary kittens.
 * Drugs Are Bad: Both Martha and the Doctor are unamused by a street populated by drug-dealing booths that sell everything from "happy" to "forget" to "honesty", and bliss killed all of New Earth's population apart from New New York's undercity.
 * Evolutionary Levels: The Doctor wonders if the Macra have devolved, considering they used to be intelligent but now they're just huge mindless mosnters.
 * First Time in The Sun: In the end, the denizens of the motorway finally ascend into the sky.
 * Flat What: Martha's reaction to the length of time the carjacking journey will take.
 * Foreshadowing: "You are not alone."
 * Giant Enemy Crab: The Macra
 * Hood Hopping: The Doctor does a three-dimensional version.
 * Hypocritical Humor: Brannigan refers to the Cassinis as 'sisters', claiming that he's a traditional type. When he's a catman married to a humanoid.
 * I Ate What: Martha is disgusted to learn that food in the cars is made from recycled waste, after taking a few bites of something offered her.
 * Interspecies Romance: The Brannigans. She's demi-human, he's a cat-man; their kids are litter of kittens (who can say "Mama").
 * Mood Patches Are Poison: When Martha finds out one of her kidnappers is pregnant, she rips off the woman's honesty patch in disgust.
 * Muck Monster: The Macra.
 * New Neo City: New New New New New New New New New New New New New New New New York.
 * Nobody Over 50 Is Gay: Averted with the Cassinis, an elderly lesbian couple.
 * One Word Title
 * Police Are Useless: A call to the police gets the Doctor put on hold. A call to the Cassinis reveal that there aren't police.
 * Planet of Hats: All of the cars the Doctor passes through have obvious themes, be they white decor, Harajuku fashion, nudism, or red decor.
 * Shout Out: The old couple in the opening who are attacked by the Macra? Take a look at the painting American Gothic.
 * And the driver with the bowler hat looks like Max Normal from Judge Dredd. The entire setting carries a whiff of Megacity One.
 * The setting, New New York, may be a reference to Futurama.
 * An airborne drug causes most of the inhabitants of a planet to lay down and die.
 * Unusually Uninteresting Sight: The people on the underground highway are disturbingly blase about the fact that nobody ever gets anywhere.
 * Villain Decay: Deliberately invoked. After a few billion years, the Macra evolved (or devolved) into a much less intelligent form, so instead of being invisible puppet masters (like the Silence would be later in New Who) they're just... giant crabs living on car fumes.
 * You Are Not Alone/There Is Another: So says the Face of Boe.