"Events are moving, Wilfred. Faster than we thought. Only you can see, only you stand at the heart of coincidence." She's right: Donna just makes a joke about the Queen's apparel and goes back to her family, in the kitchen. Wilf asks again what's so important about him, but he won't really know for a good, bad time yet. "You're an old soldier, sir. Only you were too late. The war was won and passed you by." Wilf's offended: he did his duty. "You never killed a man," she notes, and he shudders, disgusted: "No, I did not, no. Don't say that like it's shameful!" She nods. "The time will come when you must take arms." She warns him not to tell the Doctor, that his life could still be saved as long as Wilf doesn't tell, and vanishes, replaced by the Queen.
Later, he comes away from the laughter of his family and retrieves a gun from beneath a bed upstairs, wrapped in a rag. The Doctor's downstairs, hiding behind the TARDIS on the street, and Wilf goes out to meet him: He says the Master's missing, but he can still smell him on Earth. He asks Wilf again why he's the only thing connecting all these disparate stories together, and asks if he can think of anything -- like, for example, the mysterious lady -- but Wilf says no. Well, there's one thing: The random book that Donna got him, that pulls at the threads of coincidence, that sent her off into a reverie. The Doctor recognizes Naismith's face from the cover of the book, and grins: "It's all part of the convergence, maybe touching Donna's subconscious. Oh, she's still fighting for us, even now! The Doctor-Donna." Still better at this than him, dead or not.
Sylvia appears, and spotting the Doctor starts yelling. She remembers to tell him Merry Christmas before telling him to GTFO -- which is very cute, and a good reminder about how the Doctor already got Sylvia to lay off Donna and mind her manners, another gift he gave her; the actress really does work to make the different versions of Sylvia make sense -- and they all three agree one more time that Donna's the thing and that the Doctor needs to disappear. Donna comes looking for them, since now everybody's outside, and roams the house yelling for them; Wilf takes the opportunity to head for the TARDIS with the Doctor, which pisses Sylvia off, but before she can scream them to death, they're gone, and Donna appears: "Are you shouting at thin air?" she asks, adorably, and Sylvia nods awesomely: "Yes? Possibly. Yes."
Wilf stares around the TARDIS long enough for them to have the usual Companion meet-cute about how crazy big the TARDIS is, inside, and welcome aboard, and all that ritual. He asks if they can't just take the TARDIS back to yesterday and catch the madman, but the Doctor explains about how you can't move around in your own timeline -- "I have to stay relative to the Master within the causal nexus, understand?" -- and they're off.