Wow, what an episode. It's a shame Moffat said that the Christmas special will probably be his last Doctor Who episode because 'Boom' shows us that he's still got it.

This was nonstop tension, I was on the edge of my seat for the whole thing, it's also so refreshingly unique with the entire episode taking place in one location. This episode will go down as one of the all-time greats in Doctor Who in my opinion, sitting up there with stories like 'Blink'. 15 is already on the way to being one of my favourites.

A brilliant, self-contained story, thoroughly enjoyed this one.