Out in space, the probe hits a giant asteroid, in which a door opens and pulls it inside. Oh dear.
Rose and Mickey are walking down the high street, surrounded by Christmas shoppers even though it's totally Christmas Eve. Mickey gives her twenty quid for shopping and calls it her birthday present; Rose is still stuck on time travel: "God, I'm all out of sync. You just forget about Christmas and things in the TARDIS, they don't exist. You get sort of timeless." She has no idea. Mickey immediately starts bitching about not wanting to hear more TARDIS stories -- not "Doctor" stories, mind, but "TARDIS" stories, because he's smart enough to know that some words have more power than others -- and makes fun of her: "Oh! One time, in a biiiig yellow garden, full of balloons...." She protests, laughing, and says she's not like that, but we know she really kind of is. She will flip out on you and have a TARDISode before you even know what hit you. It's the price of living with one foot in two worlds. "Hmm, must drive you mad," says Rose. "I'm surprised you don't give up on me!" Mickey goes in for the two-point conversion, on that note: "That's the thing, isn't it? You can rely on me. I don't go changing my face." Good show, Mickey! But Rose has a response ready: her face falls and she gets worried again: "Yeah. What if he's dying?" Mickey stops, holding up his hands, and she apologizes again. It's sort of a valid question, isn't it? Mickey takes Rose's hands and makes her promise to just "let it be Christmas": "Could you do that? Just for a bit. You and me, and Christmas. No Doctor, no bog-monsters, no life or death." Rose promises, but of course it's a lie, and before you know it, she's staring down a brass band of Santas in creepy metal masks, playing "Good Tidings of Comfort and Joy" or whatever, because she's got a sixth sense about these things but also because she's profoundly bored by reality. Mickey: "I'm round there all the time now, you know. She does my dinner on a Sunday...talks about you all afternoon, yap yap yap yap yap..." But this whole show is about Rose wandering off in the middle of Mickey's life's story.
Of course, the Santas attack: their trumpets become flamethrowers and there are blue gouts of flame everywhere, people screaming, Rose knowing -- or assuming -- that they're the targets, hiding behind things, getting caught, screaming and running in the maddening crowd. A giant Christmas tree in the square falls to the ground on top of one of the Santas, whose mask clatters to the ground and is creepy. Rose and Mickey run down the street and hop in a taxi. "What's going on? What've we done?" asks Mickey, and Rose explains her assumption that they're after the Doctor. "I can't even go shopping with you, we get attacked by a brass band!" Rose ignores Mickey and calls Jackie, but Jackie's already on the phone. She walks around bitching about Rose turning up without warning, brings a cup of tea in, and sets it beside the Doctor, looking at him worriedly as she continues to yak. "Think about it: they were after us. What's important about us? Well, nothing. Except the one thing we've got tucked up in bed. The Doctor." And as long as you believe that, you'll do anything to stay with him. It wasn't that Rose was just a shopgirl -- it was that she didn't know she was already more than that. If it's about the Doctor's loneliness this year, it's also about Rose forgetting that she was awesome to begin with, time or no time, no matter how many times Jackie and Mickey try to explain to her: you've gotta come down off that cloud sometime, love, or you might as well be dead, and infinity doesn't mean anything at all if you don't come back and play with humanity. The difference between heroes and saints is that heroes come back, changed, and saints just disappear. Jackie leaves the Doctor with another worried look and an untouched cup of tea, and more vortex spills out of him, once she's gone.