So River finds a way to changed that "fixed point" in time and doesn't kill the Doctor, which results in time being royally screwed. The past, present and future end up coexisting in a world where Churchill is Holy Roman Emperor and pterodactyls overrun the park like pigeons. A bedraggled and slightly older Doctor is Churchill's imprisoned "soothsayer" and insistent that he needs to die for time to right itself. Before that can happen, Amy shows up wearing an eyepatch and takes him to the Great Pyramid of Giza. Which is also Area 52 and also her base of operations where she's amassed an army and captured a bunch of those Silence gentlemen, as well as Madame Kovarian. It's kind of a big, busy mess. Anyway, it turns out those patches are actually devices that allow people to remember the gentlemen instead of forgetting them the instant they're out of sight. Even in this weird, alternate timeline, Amy remembers the Doctor because she's Special. Rory is one of Amy's soldiers, but he doesn't remember anything from the original timeline.
River is also there in the pyramid and the Doctor is furious with her for screwing everything up. But she loves him and can't bear to be the one who kills him. She says in some stories, she's the woman who murders him and in others she's the one who marries him. The gentlemen escape, having just waited for the moment they could get a crack at the Doctor, which kind of begs the question of why they needed River to begin with. But in the end, the Doctor convinces River to let him go, and he does this by marrying her at the top of the pyramid and whispering something in her ear. We're led to believe that it's his name, but we later find out that he was really showing her the truth: He's actually piloting one of those shape-changing Tesselecta robots and the whole thing's been a massive pain in the ass.
There's a lot more, including the helpful appearance of blue Dorium's talking head, a tomb of man-eating skulls, a timey-wimey space beacon, sunspots and other confusion. Oh, and the question that the Silence were so afraid of? The one hidden in plain sight? See the show's title and stay tuned for the full weecap.
The episode opens on London at 5:02 PM on April 22, 2011. That things are pretty wonky is evidenced by a scaffolding of train tracks running through the big glass "Gherkin" and hot air balloons carrying hatchback cars across the sky. Also, pterodactyls chase after children for food scraps. A man on the radio says there's been lots of sunspot activity today. Charles Dickens tells a TV morning show that his next Christmas special will involve "ghosts in the past, the present and the future, all at the same time." On another program, Meredith Vieira says, "The Holy Roman Emperer Winston Churchill returned to Buckingham Senate on his personal mammoth today."
Inside, Churchill is being tended to his Silurian physician. Seems Winston is a bit flustered after his meeting in Gaul with Cleopatra. He thought she said "kiss my asp" and thinks went downhill quickly. He's also frustrated because every day, day or night, it is always exactly 5:02 and April 22. Nobody else seems bothered by this, but Winston calls for his "soothsayer." His guards fetch the Doctor from the Tower of London. The Doctor, wearing bedraggled robes and a scruffy beard, looks like he's ready to chisel out some commandments in the mountain. "All of history is happening at once," he's been saying, as Winston reminds him. "What happened to time?" Winston asks. The Doctor looks up, a bit older about the eyes, and answers: "A woman."
After the opening credits, we venture back to an earlier time. The Doctor's wearing his cowboy hat from "Closing Time" but instead of heading straight off to Utah, he's dropped in on some broken and dying Dalek. He pops its head off and sonics out some information about the Silence. The information sends him next to Calisto B, looking for a Father Gideon Vandaleur, former Envoy of the Silence. He's a man in monk's robes, with a terrible bowl cut and an eyepatch like Madame Kovarian. It's not really Gideon at all, but one of those shape-changing Tesselecta robots with miniaturized people inside. The captain from "Let's Kill Hitler" is still in charge, so hopefully they've worked out that crappy design flaw with the electric jellyfish. Robotic Gideon has been investigating the Silence, too. The Doctor wants to know their weakest link.
Whatever answer robotic Gideon gives him has him jetting off to play chess with an eyepatch-wearing sort of space viking. The match has drawn a big, rowdy crowd. It's a special kind of chess where pieces cumulatively gain electrical charge each time they're moved. The viking's queen is packing a lot of juice. If he moves it again, he'll be zapped to death. His only hope is for the Doctor to concede the game, which the Doctor agrees to do if the viking tells him why the Silence want him dead. The viking tells him to see Dorium Maldovar, but the Doctor points out Dorium was beheaded on Demon's Run. Couldn't he just go to a point earlier in Dorium's life? Guess not. "Concede the game and I'll take you to him," the viking says. The Doctor concedes.