It's entirely possible that my enjoyment of this story is owed in full to the presence of India Fisher, who I missed quite a lot. It's not Charley, but her character is fun and interesting.

Still, I don't think that's the case. It's an atmospheric story with an interesting concept which was well-realised. The twists were telegraphed and easy to predict (which I personally think is a good thing). The side characters, while somewhat flat, were all unique and served their purpose.

Five's level-headedness didn't ditract from this story for me, possibly because he wasn't in a lot of it. I always enjoy seeing (or listening to, in this case) him be put in his place, and Nyssa gets to shine as she does that. I'm really enjoying this particular TARDIS team so far.