Doctor: Matt Smith (Eleventh Doctor)
Karen Gillan (Amy Pond)
Arthur Darvill (Rory Williams)
Helen McCrory – Rosanna
Lucian Msamati – Guido
Alisha Bailey – Isabella
Alex Price – Francesco
Gabriella Wilde, Hannah Steele, Elizabeth Croft, Sonila Vieshta, Gabriella Montaraz – Vampire Girls
Michael Percival – Inspector
Simon Gregor – Steward
Directed by Jonny Campbell
Written by Toby Whithouse
Script editor Brian Minchin
Produced by Tracie Simpson
Executive producer(s) Steven Moffat
Incidental music composer Murray Gold
Production code 1.6
Series Series 5
Length 50 minutes
Originally broadcast 8 May 2010
The Doctor, believing Amy's attraction to him is due to the stress from travel, gatecrashes her fiancé Rory's stag party and invites the two of them on a romantic trip, courtesy of the TARDIS. They land in Venice in 1580 and soon find trouble. The city's patron, Signora Rosanna Calvierri, claims that the Black Plague runs rampant outside of Venice. The Doctor says this is false and that it appears she is using the plague as an excuse to seal off the city. While investigating they encounter Guido, a boat-builder whose daughter Isabella hasn't contacted him since enrolling in Signora Calvierri's school for girls.
Amy devises a plan to place herself inside the school with the help of Rory and the Doctor's psychic paper. Amy manages to unlock a gate and allow the others in, but in doing so is captured and taken to a chamber. The Doctor and Rory come to believe the women are being converted into vampires, and discover a box containing a dead figure. Amy kicks at Signora Calvierri's side and disrupts a device that is hiding her true alien form. They begin converting Amy into one of them when Isabella, who has yet to be fully converted, frees Amy and they escape. Isabella hesitates while escaping because she can no longer tolerate direct sunlight and is pulled back inside while the door closes. The Doctor tries to open the door but he gets shocked by electricity and collapses. Isabella is later thrown into a canal by Signora Calvierri and eaten by something that lives underwater.
The Doctor goes back inside to question Signora Calvierri who confirms that she and the others are from the planet Saturnyne, a race of aquatic beings with vampire-like tendencies. She and the others landed on Earth after seeing the cracks in the universe. Calvierri and her son Francesco intend to sink the city into the water and convert humans into "Sisters of the Water" in order to continue their race. When the Doctor returns to Guido's home to regroup with Amy and Rory, Signora Calvierri sends her transformed girls to attack them. Guido sacrifices himself for the others by blowing up several kegs of gunpowder that kill him and the girls. Signora Calvierri activates a device on a tower that begins to create the earthquakes and floods that will sink Venice. While Amy and Rory face and defeat Francesco, the Doctor climbs the tower and stops the device in time. The last of her kind, Signora Calvierri throws herself into the canal to be eaten, but not before tormenting the Doctor by reminding him that he is now responsible for the extinction of two species: her own, and the Time Lords.
In the aftermath of the incident, Amy and the Doctor invite Rory to continue traveling with them, but as the Doctor and Rory are about to enter the TARDIS, everything falls silent. Unnerved, the Doctor remembers Signora Calvierri's words: "We saw silence, and the end of all things..."