A pretty good entry which has as its major strength how it entwines the arc, the plot and the character development. Great and compelling stuff for Madame Vastra and Jenny, which highlights their strengths and flaws and also adds a bit of tension to them. Some very funny Strax bits too. The antagonists were interesting enough, but the secondary antagonists were great and if they weren't required for the arc I would have said that the story could have left out the aliens.