The TARDIS jumps into your average quaintly Victorian Christmas tableau: snow, wreaths, lampposts, cobblestones, stallmen shouting out their wares. It's like Disneyland, clean and shiny. It smells like FAO Schwarz and roasting chestnuts. John Smith is overjoyed by it, the crazy clothes and top hats, and applies himself vigorously and interminably to the task of appreciating it. For the purposes of this narrative, "enjoyment" means wearing a doofy grin and spinning around to cutely madrigal Christmas wassailers while the camera unendingly spins around him. It's going to be one of those for sure.
I mean, who doesn't love Christmas, like as a concept, and the whole knotted-scarf allo guvna avanappy Christmas Scrooge McDuck chim-chimminy thing especially. But you're not going to make it fresher or more lovely by forcing David Tennant to pretend he's having a half-hour aneurysm, or giving us a case of the Cloverfields, which is why it's important to pay attention: London was never like this. Christmas was never like this. Christmas is a lie; London is an engine that runs on the blood of children and the silence of women.
"You there, boy! What day is this?" The kid plays along; he doesn't know he's playing along. Nobody in London does. "Christmas Eve, sir." What year? "You fick or somefing?" John Smith jumps: "Oi!" he says. He doesn't even hear her, in his voice. "Just answer the question." It is the year of Our Lord 1851. "Nice year," he says. Especially if you like chess. "Bit dull..." he muses, which is Rosita's cue to start screaming for the Doctor.
John comes running up, and pulls her back: a statuesque black woman with a firm set mouth that tells about her bravery. He pulls her back, she continues to ignore him, screaming for the Doctor. There's something behind a door, smashing itself against the wood, trying to desperately to get out. He cautions her to get away, but she's not ignoring him. She has no time for nutters; she is a Companion to the Doctor. "No, I'm standing right here," Smith says, and offers her a hello. She fixes him to the wall with a glare like Donna's: "Don't be so stupid, who are you?"
They do the whole Doctor Who's On First for awhile, and then the Doctor shows up, much to Smith's surprise. "Where the hell have you been?" Rosita asks, and he laughs, telling them not to worry. "What have we got here, then?" And when John asks him who he is, he just smiles. "I'm the Doctor." Smith stares. "Simply the Doctor," the Doctor says, charming. "The one, the only and the best. Rosita, give me the sonic screwdriver!" John Smith is confused to the point of hilarity as she does. "Now, quickly! Get back to the TARDIS!" John's jaw drops further. "Back to the what?" The Doctor asks him to step back: "This is a job for a Timelord," he says, and John Smith's eyes bug out. "Job for a Whatlord?" The creature bursts free, like a memory. "Oh, that's different," says John, as the Doctor says, "Oh, that's new!" They hold out their screwdrivers: "Allons-y!" They cock eyes at each other. Credits.