This episode was tense from start to finish and didn't let up at all. Just a thrill ride like my favorite episodes of the show, where danger lurks behind every corner coming up against some horrific force. I completely did not expect the reveal that this was a sequel to Midnight, and it absolutely ratcheted up the intensity. The entity was behaving a little differently, but just knowing the extent of its power was enough. Plus: the reveal that the big heroic sacrifice might have been a waste of time? Jaw-dropping horror ending. This is similar to Wild Blue Yonder, these types of episodes are what Doctor Who can do better than anyone else. Fantastic performances by the whole cast too. Bravo!