Nixon tells everybody to shut up some more, and the Doctor makes himself at home in the President's chair, yelling about fezzes and jammy dodgers, and a short time later we've decided to go to Florida. ("She mentioned a spaceman, NASA's where the spacemen live.") Amy and River have a little conversation about five minutes ago when that spaceman shot the Doctor, in case you missed that part, and then Amy spots a Silent in the corridor outside the Oval Office. Rory distracts her, and she forgets about it immediately. Something happens with her womb/perception of spacetime -- same thing when you're a woman, am I right? -- and she runs off to the bathrooms (but only after Canton yells at a Secret Serve guy, of course).
In the bathroom -- "Actually, I can usually manage this alone," she tells the Secret Serviceman, which is pretty cute -- Amy recognizes the Silent in there (Same one? Different one?) as being similar to the skinny shape she saw at the lake and then forgot. A lady comes out of the john and squeals at the thing, then forgets it's there, and then squeals at the thing, then forgets it's there, and so on, until finally it just sucks out her brain juices magically, and then she is dead. Amy takes a camera phone picture of the thing, which you'd think would matter but of course never actually matters.
"Her name was Joy. Your name is Amelia. You will tell the Doctor... What he must know. And what he must never know."
I guess Amy knows what it's talking about, but anyway she forgets about that conversation immediately, left only -- and this is key -- with the burning desire to tell the Doctor something, and no idea why it's so important for her to tell the Doctor this thing.
Back in the Oval Office, the phone rings, and somehow they figure out where the call is coming from: The intersection of Jefferson, Adams and Hamilton streets. Because of course nobody is called Jefferson Adams Hamilton (River, helpfully: " Surnames of three of America's founding fathers. Lovely fellas, two of them fancied me"), clearly this was read off street signs where three streets intersect and not the, oh, bajillion other places those names just might appear together.
Kid: "It's here! The Space Man's here. It's gonna get me. It's gonna eat me!"
Everybody loads onto the TARDIS to go save the kid, cue "bigger on the inside" dinner-plate eyes from Canton, but the kid's gone. The Doctor gives a belabored explanation of the street-intersection deal, causing River to get all turned on because he's hot when he's clever, which is true, and the Doctor to joke that she looks like that all the time because he's hot all the time, also true, and Rory explains the TARDIS to still-tilted Canton.