The Doctor From Gallifrey 

WARNING: CONTAINS SPOILERS, DO NOT READ IF YOU DON'T WANT TO FIND OUT WHAT HAPPENS.

The Doctor, Rory and Amy arrive on a pirate ship to find that whenever someone gets a cut they are destroyed by a siren, who lures them with it's singing. At first the three aren't welcomed and Amy has to save the Doctor from walking the plank by having a sword fight. As the episode progresses it appears that the siren can travel through reflections and eventually the Doctor realises that they must let the siren take them as she is teleporting her victims rather than killing them. It turns out the siren is actually a doctor and is making these people better aboard a space ship. 

There is a tiny bit of story arc at the end too. Amy thinks about the Doctor's death and wonders about telling him. And the Doctor uses the TARDIS to scan Amy for a pregnancy test but the screen keeps flicking between positive and negative. What could this mean?

Well this episode was everything we would expect from pirates on Doctor Who. A bit of swash-buckling fun and an alien "preying" on pirates who actually turns out to be a force for good. It's not exactly that ground-breaking but it was fun and lighter than the previous two episodes of the series. Very enjoyable.