So while Naismith at length bullshits about how he's overruled the Master and will second-guess him and whatever, the stupid Vinvocci explain that they're only there to salvage the Gate. As for what it does? It's a medical device that repairs the body. A Doctor Gate, if you will. But the Doctor knows there's more to it than that, and finally Wilf asks the major question, which is why it's so big if it's just a sickbed. "It mends whole planets," the awful woman scientist says. "It transmits the medical template across the entire population." And girl, you know that's when the glasses come off and the Doctor starts running.
Meanwhile Naismith is just making no sense at all, yelling at the Master about Obama and how it's proof that the human race can mend its own problems, which seems like a weird point to try and score given he's the guy that just mended your problems for you, but whatever. There's a long lead-up where the President takes to the podium in a pretty explosion of flashbulbs and lens flares, and the doctor finally gets to the Gate, where he immediately starts yelling at everybody. The Master laughs at all the commotion, shucks the straitjacket, and Hulk-jumps into the Gate, and then before you know it he's turned the entire globe into more of him. The President, Sylvia and Shaun, everybody. The only humans left are Donna, because of her Time Lord DNA, and Wilf, because he's standing in that Nuclear Lockdown thing when it hits. Donna's brain starts melting as she remembers things -- the Wasp, the Rachnoss -- and everywhere on earth the Master looks back at you.
"The human race was always your favorite, Doctor, but now there is no human race! There is only the Master Race!" Boo. All the six billion Masters laugh and point at everybody else; down in the street one of them throws a hat, and another one mysteriously catches it. That was pretty awesome.
SEVEN: A Secret, Never To Be Told
"This is perfection. I have created Heaven on Earth." Only a fake bastard God could think that was beautiful.
There are two kinds of faith: stupid and smart. There's the kind of faith that keeps you in the rat race, heading for this Utopia on the highway of life, giving up all personal determination, all free will, because somebody told you one time that it's going to get awesome as long as you don't go too low, don't reach too high, don't talk too much, don't ask questions, don't disobey.