Jenny found her way to a remote, locked room, and discovered a creature being held captive. The creature was, in fact, our beloved Doctor, his skin completely red, his mouth frozen in a state of shock. Ada had kept him captive as a friend, calling him "Monster." He sure looked the part, stumbling around like Boris Karloff in Frankenstein. Jenny led him into the re-light room, while poor blind Ada stumbled around behind them. She told an empty room: "There will be room for us in the New Jerusalem."
Inside the red room, Ada saw The Crimson Terror: A vat of red liquid that the denizens of Sweetville were dipped into. The Doctor managed to get better, using the healing green light of the Sonic Screwdriver. He was his old self again. He took Jenny in his arms and kissed her; she slapped him; "You have no idea how good that feels!" he exclaimed.
He told her the full story: The flashback played off in mock-old-timey film. (I kind of wish they'd fully committed to the gimmick and made it a silent-movie homage, but this episode was overstuffed as it was.) The Doctor and Clara arrived days earlier, aiming for London and winding up in Yorkshire. Clara was dressed up in Victorian dress; she looked more than ever like Clara Oswin Oswald, the sassy maid from "The Snowmen. (ASIDE: Is The Doctor's relationship with Clara starting to remind anyone else of Vertigo? END OF ASIDE.)
They investigated Sweetville, entering themselves into the community as Mr. and Mrs. Smith. (They were working with dearly-departed Edmund -- yet again, this fast-paced episode quickly downloaded a whole episode of plot in just a couple minutes.) In the flashback, we learned that Mrs. Gillyflower had a "silent partner": Mr. Sweet, who liked to "keep himself to himself."
They also saw an attractive young couple, who appeared to have been turned into mannequins in a snowglobe. That was the purpose of the Crimson Terror: A process which preserves everyone, in preparation for a new life after the coming apocalypse. The rejects went into the Canal; but the Doctor survived, and was rescued by Ada. The dying Edmund found his way into the Doctor's cell, which is why his image was imprinted on the corpse's eye.
Meanwhile, Strax was lost in Yorkshire. He threatened to shoot his horse: "Fourth one this week. And I'm not even hungry." But a charming young street orphan named Thomas Thomas guided him along. (I assume the name is a reference to an awesome British thing I don't know about.)
Blind Ada told her mother about the monster. Mrs. Gillyflower decided that she had to hasten her dark plans. Ada begged her for a place in the New Jerusalem. "Do you not yet understand?" her mother said. "Only perfection is good enough for myself and Mr. Sweet." She left her daughter crying in the cell.
The Doctor needed to go find Clara. Jenny was confused: "Clara's dead, isn't she?" The Doctor answered; "It's complicated." Sure enough, the Doctor tracked down Clara, preserved inside one of the snowglobes. He tried curing her, but Jenny pulled off her undercover clothes, revealing her all-leather attack gear. She took down a few of them; then Strax appeared, in his space armor, and took down the rest with his cool laser. Vastra was there, too: The whole gang, back together, all confused about the idea that Clara was still alive. "I know who you think she is. But she isn't. She can't be."
NEXT: The secret in the chimney