The Vampires of Venice is the sixth episode (and fifth story) of the fifth series of the revival of Doctor Who. It stars Matt Smith as The Eleventh Doctor, Karen Gillam as companion Amy Pond, and reintroduces Arthur Darvill as semi-regular Rory Williams, the fiancé of Amy.
After their last adventure, Amy Pond worked out some of her pre-wedding jitters and near-death anxiety by attempting to seduce the Doctor, in a scene that was both racy and humorous. Attempting to "sort Amy out", the Doctor finds her fiance, and takes them on a nice romantic trip to Venice, figuring that is a pleasant romantic location. Unfortunately, there is something going on in Venice, and strangely enough, it involves monsters that turn out to be aliens.
As a side note, it should be pointed out that for many other television shows "I've seen this plot five times!" would be a sign of disapproval, for the Whovian, it is a sign of affection. After all, it was just last series that we saw an alien race fleeing their doomed star and attempting to take over a Mediterranean city. And it was only a few years ago that we saw another refugee alien race attempting to pass themselves off as supernatural entities. Twice.
So it isn't the basic plot that makes this episode interesting. It isn't even the development of the arc plot with the cracks in time and the references to "silence will fall". Instead, what makes this episode interesting is the comedic love triangle between Amy, dependable Rory, and the adventurous Doctor. The best scene of the episode comes not from the Fish/Vampire/Aliens, but when the Doctor bursts out of the cake at Rory's bachelor party, and excitedly tells him that his fiancé is quite the kisser. Any Doctor could have fought aliens masquerading as vampires, but only Matt Smith's Eleventh Doctor could tell a man on the eve of his wedding how his fiancé tried to seduce him, and think it was a compliment.
The entire situation with The Doctor, Amy and Rory, would be further explored in the next episode, Amy's Choice.