"If I give my name, they'll know they've found the right place," the Doctor says, "and that it's safe to come through." He says all hell would break loose. He gives Clara something to plug into the TARDIS console. While she does that, Tasha projects her big giant head over the town square. "There's only one thing I need from you," he says. "This planet -- what's it called?" She waits a dramatic beat and then says, "Trenzalore." He's been there before; how did he not recognize it? Is it not in the same place it was when he visited it in the future? Tasha says the Time War will begin again if the Time Lords return. Why? Who knows?
Much to Clara's dismay, the TARDIS has brought her back home. She runs back to it just as it begins to warp away again.
"Speak your name and this world will burn," Tasha's head warns. The Doctor summons all the townsfolk and introduces himself as their new sheriff. Up in the Papal Mainframe, Tasha alerts the faithful that there's been a change. "From now on, I dedicate this church to one cause: silence. The Doctor will not speak his name, and war will not begin. Silence will fall!" The soldiers and assembled nuns repeat this same imperative.
Time passes. Lots and lots of time passes. Tasha tells us in voice-over (for it was her voice in the beginning, as well) that the Papal Mainframe "maintained the peace" between the Doctor and his enemies. The accompanying montage doesn't look entirely peaceful, though, as the Mainframe blasts away every intruder approaching the town. To slip past the town's defenses, the Cybermen create a wooden version. A little boy is first to spot the new foe and runs for the Doctor. The Doctor hobbles out of the tower, leaning on a walking stick, his face a bit soft and wrinkly. He soon tricks the wooden Cyberman into destroying itself. All the citizens of Christmas celebrate and throw a party. "The people of the town came to love the man who stayed for Christmas," Tasha says. It's awfully nice of them not to blame him for their troubles, since he's the one all these aliens are trying to destroy and they're the ones in the crossfire.
It's during one of these joyful parties that the TARDIS finally returns. "Where have you been for 300 years?" he demands to know. "Does this mean you're leaving?" a little boy asks. His name is Barnable, which sounds like a portmanteau of Barnes & Noble. The Doctor doesn't answer him, but heads over to the TARDIS, the outside of which Clara is still clinging to like a suction-cupped Garfield toy. For a few moments, she can hardly move or speak, so stunned is she from her journey through the time vortex. Then she's mad at him for tricking her, but it only lasts for a second and then they're laughing and hugging.