SPOILERS BEHIND THE CUTS
The Doctor crashes the bachelor party of Amy's fiance, who is revealed to be Rory (aka the male nurse from The Eleventh Hour. After telling Rory that he snogged his fiancee in front of all his friends, The Doctor drags him off to go on a romantic trip with Amy. Why? Well, The Doctor figures that the stress of time travel was getting to her - which is what led to the whole "take me now" incident last episode - and that sooner or later relationships where one person has traveled in time and the other one hasn't are doomed to fail.
So they go to Venice in 1580. Nice romantic setting spoiled only by an outbreak of the plague and everyone getting dragged into a mystery involving creatures that appear to be vampires after only being on the ground for five minutes.
The Doctor's attention is grabbed after he sees Guido - a man who gave his daughter over to the girl's school run by local noble Rosanna Calvierri - trying to find his daughter among a series of veiled girls, only to be horrified when he finds his own daughter doesn't recognize him. Meanwhile, Amy and Rory discover Rosanna's son Francesca draining the fluids from a local flower girl in a shaded alley. The Doctor manages to sneak inside the school briefly, but flees after discovering that all the girls in the school have fangs and do not appear to cast reflections.
The four reconvene and discuss what they know. Amy quickly comes up with a plan that Rory will pose as her brother, put her in the school and then she can unlock a storm gate which connects to a tunnel under the school that Guido discovered. The plan does work, but it turns out that Madame Calvierri saw through Amy's psychic paper credentials and Amy is taken into the basement shortly after unlocking the gate and locating Isabella, Guido's daughter.
Amy discovers that the "vampires" are indeed taking young women and changing them into creatures like them but that instead of sucking blood, they suck all the water out of their victims before injecting them with their own blood. This triggers a transformation that either kills the victim or changes them into a "vampire". Amy is also told that she will soon have her pick of over 10,000 husbands.
The good news is that Isabella recovers enough of her senses to help Amy escape. The bad news is that she is unable to exit out of the tunnel (the light is too bright for her) and she is quickly recaptured. She is then made to "walk the plank" over the canals of Venice for being a traitor and no sooner does she hit the water than she is pulled under by... something.
It is here The Doctor decides to take the direct approach and just breaks into the school alone, catching Madame Calvierri alone in her throne room and offering to trade an answer for an answer. She agrees because she's awfully curious as to who is running around 1580 Venice with psychic paper. The Doctor reveals himself as a Time Lord and Madame Calvierri explains why she and her students appear to be vampires with a wonderful bit of Whovian technobabble.
(Short answer: their race is naturally sensitive to intense light and heat, a bug in the device that makes them look human makes it unable to replicate reflections and their lamprey-like teeth show up as normal due to a "self-preservation loophole")
We find out that Madame Calviverri is the last female survivor of a fish-like race known as the Saturnynian and that she and her sons became trapped on Earth in this time period after a crack in reality opened, destroying their world. Most of her sons are living in the canals of Venice, unable to stand the light of the surface. Her plan was to take in unfortunate women - who probably would have died anyway - and change them into women of her own species, in order to insure that her race will continue on. She asks the Doctor to help he with establishing a new colony elsewhere, which he flatly refuses to do after learning that they killed Isabella because "you didn't even know her name!"
Make a long story short (too late) Guido dies after blowing up his own house to destroy the vampire girls, Amy kills the one male human vampire with sunlight reflected by a mirror and The Doctor disables a weather control device Madame Calviverri was going to use sink Venice. Defeated, Madame Calviverri - still disguises as a human woman - throws herself to her own sons and is devoured, shortly after telling The Doctor that he shall have yet another dead race on his conscience. As the group are leaving Venice, with Rory having agreed to travel a bit longer with The Doctor and Amy, an eerie silence - like the one Madame Calviverri described - falls over Venice.
THE GOOD PARTS
* The dialogue here sizzles and there's a lot of good comedic moments. Small surprise given that this was written by Toby Whithouse - the same bloke who wrote the Second Season episode School Reunion.
* The mystery around the Vampires is a good one and the technobabble regarding them highly plausible - at least by Doctor Who standards.
* The conceit that The Doctor is actually trying to help preserve Amy and Toby's relationship after his experiences with Rose Tyler and Mickey Smith is a nice touch.
* They are REALLY inconsistent about just how badly sunlight affects the vampires. One focused sunbeam reflected in a mirror is enough to trigger a fiery explosion and the girls all walk about the town in heavy veils. But pulling the veils off during the day doesn't seem to have any ill physical effect and at the end Madame Calviverri is able to walk about on a relatively clear day in her nightgown with no apparent ill effects.
* Rory isn't very well developed as a character. In fact, the best way to sum up his character and role in the episode is this.
1. Take Season One Mickey Smith.
2. Take out all the charm and competence.
3. Make him a white boy.
That's Rory in a nutshell so far. Even his speech where he tells off The Doctor for making people do dangerous things to impress him comes off as a bit weird, given that Rory barely knows The Doctor at this point. No offense, but it's hard to see why Amy got engaged to the twit and not at all hard to see why she ran off with The Doctor the night before her wedding.
* Speaking of Amy, I've been joking about how this has become The Amy Pond Show (indeed, there's even a Facebook page devoted to this concept now) but now it really does seem to be the reality, with Amy calling The Doctor and Rory "her boys" and The Doctor not arguing at all with the concept.
* There's one major problem with the core idea of this episode. And I'm going to discuss that in a new regular part of these reviews that I call...
THE DOCTOR'S DICK MOVE OF THE WEEK
We've pretty much established at this point that The Eleventh Doctor is a colossal dick. So from now on, rather than discussing my current opinion on the newest Doctor's personality, I'm going to chronicle the many ways in which he practices what is known in the American vernacular as "Superdickery".
This week? The fact that there is no good reason for The Doctor NOT to offer to help Madame Calviverri and that his direct actions doom an entire race to extinction.
Hear me out on this.
Yes, she is a technical and actual murderess - having basically ended the lives of dozens of young women and actually killing several others in the process or to cover up her secrets.
Yes, she is plotting to destroy an entire city for the sake of her family and her species.
But she offers to stop.
She asks The Doctor for help.
She says she'll be happy to set up a colony elsewhere and start her species anew someplace besides Earth... and the Doctor refuses her because she didn't know the name of one Earth girl he never even met past a few seconds running away from the vampire hordes?
Now, granting that it is totally in character for The Doctor to hold someone he likes (or, rather, the daughter of someone he likes, but let's not quibble on that point just yet) as being more important than the welfare of an entire race or the sanctity of the time-line, there are two things we have to consider.
1. This Isn't The First Time The Doctor Has Been In This Situation - The Doctor being asked to help save a dying race who is perusing questionable means to continue their existence is hardly a new occurrence. Just from the new series you have the Gelth from The Unquiet Dead, the Krillitane in School Reunion and the Human/Dalek hybrids in Evolution of the Daleks.
And in all of those situations - even when dealing with his worst enemies - The Doctor was always willing to consider helping them out until a better solution could be found. Which brings us to...
2. He'll Save The Daleks But Not The Saturnynian? - Seriously? He offered to save Davros and The Daleks in Journey's End and they're a HELL of a lot less innocent than Madame Calviverri and her sons! Davros was a mad scientist of the old-school who was out to rule the universe through genetic engineering before going completely insane and setting out to destroy the universe. The Daleks are born and bred fascists out to destroy everything that isn't 100% genetically pure Dalek by their standard. Not much chance for reform, there.
Compare that to the Saturnynian who - yes - are a race of monsters straight out of Lovecraft (fish-people changing human women into their own race for breeding purposes... why does that seem familiar?) but whom have only resorted to doing this to keep their species going after their home world was destroyed by an accident that The Doctor seems to be at least partly responsible for. They're monsters but at least they have a motivation beyond "EXTERMINATE!" and have been trying to mitigate the damage by limiting themselves to converting women who were going to just die anyway. And sure - they were going to destroy the whole city - but The Doctor didn't know that until AFTER he'd already refused to help them.
When you get right down to it, the only reason The Doctor won't help is because Madame Calviverri didn't bother to learn the name of some person whose identity she was erasing anyway and whom The Doctor NEVER EVEN MET!
The Final Verdict: A brilliant premise and sparking dialogue can't disguise inconsistent rules regarding the vampires, the utter blandness of Amy's fiance and The Doctor's own hypocrisy when it comes to just when he can be arsed to save someone.