Written by Mark Gatiss.There's something very odd about Mrs. Gillyflower's Sweetville mill, with its perfectly clean streets and beautiful people. There's something even stranger about the bodies washing up in the river, all bright red and waxy, with an expression of absolute horror on their faces. Madame Vastra, Jenny Flint and Strax are contacted by a dead gentleman's brother and decide to go up to Yorkshire to investigate.Mrs. Gillyflower is recruiting people in the local church, where she shows the crowd her beautiful blind daughter Ada. The young woman was blinded and heavily scarred by Mrs Gillyflower's husband, and in response, Mrs Gillyflower decided to provide a safe haven for all those who want a better way of life. Sweetville mill only takes the best and the most beautiful. Jenny decides to infiltrate into the mill, where she finds the chained "monster" that Ada has come to love as her pet over the last few weeks... the Doctor, severely paralyzed by the crimson horror. His skin is dark red, his mouth is frozen wide open. His Bizarre Alien Biology allowed him to survive the process that killed many other "discarded" gentlemen and ladies, and Ada hid him from her mother as her own private pet. With what little motion he has left in his limbs, the Doctor manages to show Jenny how to restore him back to normal, and explains that Mrs Gillyflower is running a scheme rather more sophisticated than a simple mill. Apparently, it involves a never-seen gentleman named "Mr Sweet". Vastra, meanwhile, recognises the crimson horror from her own time period.The Doctor and Clara were captured when he tried to take her to Victorian London and figure out a bit more about her mystery. The TARDIS landed them in Yorkshire instead, where they decided to investigate the crimson horror and were promptly captured while attempting to infiltrate. Once Clara is freed (to Jenny's great confusion — after all, she saw Clara die last time), the Doctor finds Ada and reveals himself to her as her "monster", before confronting Mrs Gillyflower. The old woman reveals that she's got a prehistoric red leech — Mr Sweet — stuck to her chest, and plans to spread its infection across the planet to kill all but her "best and most beautiful"... using brainwashed labour forced to build a Steam Punk rocket. Ada is mortified to be betrayed by her mother, especially once the Doctor calls Mrs Gillyflower out on being the cause of Ada's scars. While Vastra and Jenny neutralise the rocket, Mrs Gillyflower is defeated by Strax and spends her final moments complimenting Ada on her ruthlessness. The Doctor proposes to take the leech back to its proper time period. Ada hacks it to bits with her cane instead.In the aftermath, Clara takes a break to head home and spend some time with her replacement family. Angie and Artie, who know a good adventure when they see one, have done some internet research and found pictures of Clara across time — including one from Victorian London, instead of Yorkshire. Clara's confusion prompts her to reveal her time travelling secret to the kids, who insist on coming along.
Abusive Parents: When we're introduced to Ada Gillyflower, we're told that she was blinded by her father. It's later revealed that Ada's scarring actually came from experiments done by her mother.
Action Girl: Jenny steps up for a bit of unarmed combat.
The Doctor and Ada share many, including a very sweet kiss on the cheek.
And Clara's tapping the Doctor's forehead ranks as one of the cutest moments in the show's history.
And I Must Scream: Slightly downplayed with the Doctor — he can move... barely, and he can't make any noise except for unintelligible groans. His reaction to the Armor-Piercing Slap also implies he couldn't feel touch either.
Anti-Villain: Ada is not malicious, just firmly under the control of her mother.
Anywhere but Their Lips: After snogging Jenny earns him a slap, the Doctor restrains himself to kissing Clara on the forehead and Ada on the cheek.
A-Team Firing: During Strax's Big Damn Heroesmoment, he fires at a bunch of Sweetsville residents in a narrow hallway but injures nobody. Could be a subversion: both the Doctor and Jenny were on the way, so he — maybe instinctively, if he's that good — fired away from them to scatter the group and then kept on out of, well, sheer being himself, after the bad guys had ran.
Badass in Distress: Jenny finds the Doctor chained up in a room after being paralysed by Sweetville's process. Subverted when it turns out being chained up in a room and hidden away is what saved him, but he was still unable to do much in his state.
The Doctor: Mrs Gillyflower, you have no idea what you are dealing with. In the wrong hands, that venom could wipe out all life on this planet. Mrs Gillyflower: (holds out her hands) Do you know what these are? (laughs) The wrong hands.
Big Damn Kiss: When the Doctor is brought back into the game, he dips Jenny and gives her a big smack on the lips. Lesbian, married Jenny. She smacks him in return — with her hand.
Black Comedy: Strax advocates a full-out assault on Sweetville as the casualties would only be 80% (i.e., only one of them would survive), and prepares to disintegrate his fourth horse of the week when he gets lost (and he wasn't even hungry).
Clara's charges found photos of her in the past with the Russian submarine crew and the ghost hunters from earlier, as well as her recent adventures in Victorian England. Except the last one wasn't her, but one of the other Claras the Doctor has met.
While passing himself and Clara off as a married couple interested in Sweetville, the Doctor speaks in a heavy Northern accent reminiscent of Nine.
The Doctor borrows Five's "Brave heart" catchphrase (and not for the first time). This could be a Shout-Out to The Avengers considering Diana Rigg.
Clara asks the Doctor if he's had enough of "Victorian values" before she boards the TARDIS at the end of the episode.
The superstition of an eye retaining the last image it sees was previously referenced by the Fourth Doctor, who then used a similar process to read the last images recorded in the brain of a deceased Wirrn.
Convection Schmonvection: Apparently, all you need to do if you're within two feet of a rocket motor running at full power is turn your back, and you'll be fine.
The Coroner: The mortuary attendant who shows off the red corpses.
Engineered Public Confession: The Doctor tricks Mrs Gillyflower into admitting that she experimented on her own daughter, causing her blindness, when her victim is just outside the door.
Enhance Button: Invoked. The Doctor's comment that the human retina can retain an image upon death leads to the coroner taking a photo of the deceased's eyes. Vastra and company enhance it the old-fashioned way ie. in the darkroom, and get their first clue.
Evil Cripple: Subverted. Ada is blind and was initially helping her mother's evil plan, but saves the Doctor and is shown to actually be a very decent person.
Follow the Chaos: Not for the first time is this a reliable way to locate the Doctor:
Vastra: To find him, she needs only ignore all "Keep Out" signs. Go through every locked door and run towards any form of danger that presents itself. Strax: Business as usual then? Vastra: Business as usual.
For Me It Was Tuesday: Thursday visits Vastra and gives Jenny a piture; Jenny frowns and, at the sight of it, Vastra says "Good grief" and raises her veil. At the sight of her, Thursday gasps "Oh, god" and faints. Vastra merely rolls her eyes and shakes her head at this implying it is a regular occurence.
Genre Savvy: At the end of the episode, Archie and Angie know a time-travelling alien when they see one.
The Doctor gets one; when Strax, a Sontaran, is wildly firing, he wisely moves aside looking very frightened.
Sherbet has been used in parts of both the UK and Australia as slang for an alcoholic drink, especially beer. This use is noted in a slang dictionary as early as 1890, and still appears in list of slang terms written today (especially lists of Australian slang). "We're heading to the pub for a few sherbets." - ... pints of beer. In the UK "Showbiz Sherbet" sometimes refers to cocaine, which is also consumed as a powder.
Guinea Pig Family: Mrs Gillyflower experimented on her daughter to devise an immunity to the red venom for herself.
Improvised Weapon: A chair can be used to destroy a control panel just as well as a sonic screwdriver.
In Medias Res: The episode begins with Vastra and Jenny getting involved, after the Doctor and Clara are already on the scene. The part of the story that would normally be the beginning gets told in flashback once the Doctor and Jenny meet up.
Madwoman in the Attic: Ada is keeping a pet "monster" locked up in a side room. It's the Doctor, reduced to near-zombie status by "rejection".
Mistreatment-Induced Betrayal: Ada can't bring herself to betray her mother, even after she finds out about her schemes. But when she finds out that Winifred caused her blindness, she dashes toward her, practically frothing with rage.
Saying Too Much: Clara insists that the photos her charges have found are a complete coincidence — until she spots one from "The Snowmen" that she doesn't recognize.
Angie: You were in Victorian London. Clara: No I wasn't, I was in Victorian Yorkshire— (whoops)
Seen It All: If you really look at it, apparently Thomas Thomas has. He had no objections to hopping in a carriage and driving off with a giant talking potato who had just threatened to shoot and eat his horse right in front of him.
Sense Loss Sadness: The Doctor spends a few weeks struck by the crimson horror, completely numbed.
The name of the Street Urchin who gives Strax directions is Thomas Thomas. As in the GPS/Satnav Tomtom. He even talks like one.
What do you do with a Sweet? Suck. What does Mr Sweet do? Suck.
When Mrs. Gillyflower learns that she has been discovered, she decides to accelerate her plans and launch her rocket, and we see her doing so by means of a church organ; pulling out all the stops.
Steampunk: The devices used to simulate the sounds of a busy factory, a Babbage Engine launch system and the rocket. Noteworthy in the fact that unlike most Doctor Who episodes there is no Anachronism Stew with alien technologies.
When Jenny and the Doctor are found by Mrs Gillyflower's pretty mooks.
The Doctor: Great! Attack of the supermodels. Time for a plan. (Jenny hits people) The Doctor: ... That is a plan.
The question comes out again right afterwards — posed by the sheer number of people, right after Jenny provides her answer. This time, Strax bursts in, providing the same answer. Only louder and with More Dakka.
The Doctor also plans to take the Red Leech back to its own time period. Ada just hits it with her cane. Repeatedly.
The Doctor tries to configure his sonic screwdriver to make the control panel stop the missile launch. Clara just throws a chair at it.
Strax tries advising this trope at times, but gets ignored by his fellow team members.
We Need a Distraction: Jenny pays a woman to fake a fainting spell so she can break into the secret section of Sweetville.
Wham Line: Works another way — the present Clara now knows about the Victorian Clara.
Yandere: Downplayed. Ada is a mild example for the Doctor, which is why he's in the attic and not dead. It's played for sympathy, as we get the feeling that she's so broken that her creepiness is the only way she can express affection and sympathy. The Doctor also doesn't seem to mind either, once he's back to normal.