OK, I think we’re passed the reasonable “no spoilers” time for this. I may not be so kind when it comes to future episodes, though…
So, where to begin? I think I’ll avoid my usual high-speed plot summary on the grounds that any summary I attempted would either be outrageously long or outrageously incoherent, and more than likely both. Instead, I’ll touch on some of the events, and babble a bit about how this all fits in with previous and forthcoming episodes.
For much of last year’s series, the Doctor was being warned that not only would the Pandorica open, but silence (or perhaps Silence) would fall. Well, the Doctor sorted out the little matter of the Pandorica, only needing to reboot the whole universe to sort things out, but that still left a few unanswered questions, such as what made the TARDIS do the explody universe destroying thing, what the Silence thing is all about, and above all who the hell is River Song?
Amy and Rory, having not seen the Doctor for a few months, other than his odd appearances in Laurel and Hardy movies and some bizarre historical adventures, receive a blue envelope with instructions to go to a particular location on a specific date. Off they go, where they meet the Doctor, who pauses only to have his stetson shot off by River Song and to mention that he’s a couple of hundred years older than he was last time they all met, before being killed stone dead by what appears to be an Apollo astronaut who strolls out of a lake. Yup, dead. Killed while trying to regenerate. Really really really dead. You know, the kind of scene that anyone less than Steven Moffat would have used as the world’s biggest cliffhanger, but instead is used to set the scene for the episode. The man’s quite bonkers…
Anyway, joined by an gentleman who introduces himself as Canton Everett Delaware III, our surviving heroes pop off to a local cafe, where they’re joined by someone else who’d received an invitation to be in the Utah desert on that day: the Doctor. Yes, he’s back, or at least not dead yet, what with not being his 200 year older dead self.
And that’s where it all starts to get interesting. It seems that throughout human history, people have been used and manipulated by a parasitic alien race known as the Silence, who look something like a cross between your usual standard issue alien-abduction-style Grey, dressed up like MIBs, and with a slight trace of the Edvard Munch Scream about them. Oh, and you’re only aware of them when you can see them, as they immediately wipe your memory as soon as you look away. And they can implant instructions in your mind.
More fun follows, with a trip back to 1969, where we meet a much younger Canton Delaware, who was booted out of the FBI because of who he wanted to marry. We also meet Richard Nixon, Apollo 11, and lots of the Silence.
And there’s a strange child who keeps phoning Nixon for help. The Doctor tracks her down to a location in Florida, where there’s more fun with the Silence, and a figure in an Apollo spacesuit, which prompts Amy to grab a gun and shoot, thinking that maybe if she stops it in 1969, it won’t be around to kill the Doctor in 2011.
Obviously aware that the Doctor poses a major threat to their ongoing occupation of Earth, they arrange to have him incarcerated in Area 51 behind the traditional impregnable wall, where he’s joined by body bags containing Amy and Rory. Fortunately, he’s been helped by Canton, so Amy and Rory aren’t actually dead, and he’s been locked up with the TARDIS, which now has a handy invisibility screen.
And more fun follows, with that mysterious child, the Doctor’s Cunning Plan to drive the Silence off Earth, Richard Nixon being advised to record everything that happens in the Oval Office to avoid problems with Silence-induced memory loss, and more confusion and oddness than you can shake a sonic screwdriver at.
For River Song, the end of this adventure is hard – she realises that it’s the last time she’ll kiss the Doctor, what with it having been the first time for him, and she’s aware of her impending mortality.
And there’s a final, spectacular moment of WTFery. That strange little girl, who was cooped up in an Apollo spacesuit full of assorted alien technology? Well, we see her in an alleyway. She tells a nearby person that she’s dying, but it’s not a problem, she can fix that. And she starts to regenerate. Who. The. Heck. Is. She????
And there’s the little matter of Amy’s pregnancy. Which, according to the TARDIS, seems to be in kind of quantum wossnameness, alternating between yes she is and no she isn’t.
Then there’s the punchline to the Canton Delaware thread. The Doctor suggests to Nixon that he should get Canton back into the FBI, as after all, wanting to marry someone isn’t a good reason to lose your job.
This being 1969, Nixon, asks:
This person you want to marry – black?
To which Canton replies
Yes, he is
Which is a bit much for old Tricky in 1969, but nicely done.
Or, to summarise all that:
What?!?! How?? Wibble!
The problem, such as it is, with this opening two-parter, is that much of it won’t make sense until later in the series. Some things might be cleared up by the mid-series cliffhanger, others not until right at the end of the series. And if I know Steven Moffat, he’ll probably add some fresh fun to lead into next year’s series. Deeply mind-boggling stuff, and the kind of thing you really have to pay attention to when you’re watching if you’re going to have the slightest chance of working out what’s going on. And when you do work it out, you’ll probably be wrong.
 A gloriously silly and contrived one, of course.
 This may have led to unintended consequences later
 Which we’ve already seen, of course