Concerned that Amy’s relationship with Rory might not be entirely stable following her ever so slight pass at him after sorting out those Angels last time, the Doctor decides to take action. He drags Rory away from his stag night by means of taking the place of the stripper in the huge comedy cake. In deference to him being a 900+ year old Time Lord, he did keep his clothes on, however.
He takes Amy and Rory for a nice visit to Venice in 1580, where something a wee bit odd is going on. Quite apart from the city being closed to outsiders to keep the plague out, even though it sort of died off a few years previously, there’s the little matter of the school for young ladies being run by an only moderately sinister lady and her only a wee bit creepy son. The quite impressive fangs are an optional extra, it seems.
Lots of running around and general silliness and fun follows. The Doctor leaves Amy and Rory while he has a look at the school, and they separately come to learn that Venice appears to have a vampire problem. While Rory is moderately worried by this, the Doctor and Amy are delighted, both jumping up and down in excitement…
There’s a lovely gag where the Doctor, meaning to flash his usual psychic paper, instead produces a library card. We only see it for a moment, but the picture on it is quite clearly the First Doctor. Sweet.
In order to find out what’s going on, Amy applies to join the school, which looks like a slightly low-budget Hogwarts, except the staircases are marble and don’t move so much. Or at all, for that matter.
Oh, and there’s a lovely exchange between Rory and the Doctor
She kissed me!
And you kissed her back!
No, I kissed her mouth
All of which is an aside, of course. Amy is in a bit of bother, and learns that the “vampires” appear to be something else in disguise. After she’s rescued by the Doctor and Rory, things start to get much more interesting.
We learn that the vampires ended up on Earth after getting isolated by one of those dodgy cracks, that they use perception filters to make them appear human, and that while Venetians can swim, they’re not immune to being eaten by psycho fish from space.
Rory gets into a sword fight. Well, the other guy has a sword, Rory makes do with a broom. The Doctor foils the Cunning Plan to sink Venice, and they all live happily ever after.
Amy, with the Doctor’s cheerful agreement, invites Rory to join them on their travels.
As always, there was a lot more going on than I’ve mentioned here – this story was more of a romp than the last one, and none the worse for that. All very nicely done, and a lot of fun.
 The guy she’s supposed to be marrying tomorrow. Err, the day after she left with the Doctor. Err, whatever wibbly wobbly timey wimey relationship with “now” works for you
 Do they still do the cake thing? Really??
 I’ve got a right to know – I’m getting married in 430 years!
 Mad bit of bell-tower climbing
 Apart from the Fish From Space