Amy and the Doctor run into each other's arms and dance around, super queer as Rory watches, yelling about vampires. The Doctor's sort of a jerk to Rory, but that's nothing new. The Doctor decides they need to get into the house -- a place he just was -- but that for some reason this time it's going to take an incredibly complicated plan that it takes like half of the episode to discuss. They head over to Daddy's house, and he says that the House of Calvieri is like a fortress and you can't get in, even though they just got in.
This part I'm unsure about, plotwise, but the actual reason for the scene is so they can talk about Amy like she's not even in the room, basically whether or not it is meet to send her in like a Charlie's Angel and pretend to be a proto-Veela so that... Something, I dunno. A trapdoor is involved. Don't worry about it. There's a really cute moment where Rory realizes he's sitting on a ton of gunpowder, and the Doctor puts his hand on Rory's shoulder and plays it cool, and they are both neat. The point is that the Doctor and Rory both have ideas about Amy's safety, and Amy is a goon so she has no feelings about her own safety, so once again she'd be better off listening to the menfolk. And secondarily, the Doctor gets his way.
So then Rory is going to pose as her brother, a gondola driver, and there's sort of an icky thing where Amy asserts that Rory is more believable as her brother, while the Doctor is more believable as her boyfriend -- not her father, given that he looks about nine years old -- or something. It squicks everybody out, even Isabella's dad who hasn't had to sit through this shit all season. The Doctor is like, "Can we please not talk about this even though I keep setting it up to talk about this." Luckily, he's so great that he sells even this.
They head into the Veela school and Rory does a bunch of cute stuff, and they think about how Amy is just perfect for getting raped by fish, and old Frenchy licks his lips and whirls around and does a back handspring and whatever is ridiculous and fey, and they kick Rory out and she's like, "Tell Uncle... Doctor... I'll see you both pretty soon, okay? I'll be fine!"
I bet she won't be, but then she will be, and then it'll be dicey for awhile, but everything will work out in the end. I also bet that the Doctor is going to save Venice somehow, and everybody will clap for him like that time he took a ride in a balloon. So they stick Amy in this Spartan sort of cell and she meets Isabella, who is well down the road to becoming a vampire lady: "They, um... They come at night. They gather around my bed and they take me to a room with this green light and a chair with straps, as if for a surgeon." HOW AWFUL. Hearing about this stuff is much scarier than seeing it. End result: "I wake up here. And the sunlight burns my skin like candle wax."