I mentioned in my review of the previous episode, “Oxygen”, that I’ve found Series 10 to be the most consistently good series of Doctor Who in a long time. This opinion has definitely not changed. However, one of the things I’ve particularly liked about the earlier episodes of the series is that they have stopped focusing heavily on the show’s past and instead have started looking forward to new ideas and new journeys. In “Extremis”, the show does start looking to the past again. This isn’t necessarily a bad thing, and in fact, Doctor Who should never completely disregard its past; looking to the past ought to happen from time to time.
“Extremis” handles this very well. Its use of the past helps to build its future. However, “Extremis” is also a somewhat less accessible episode to newer viewers than the previous five have been. Considering that this series has been deliberately structured to be an ideal “jumping-on” point for new viewers, I do wonder if “Extremis” might be a bit of a misstep—not a big one, but a little one. It will depend a lot on what happens in future episodes.
Whether it is or not, “Extremis” is still an excellent episode that I enjoy immensely. It has a wonderfully foreboding atmosphere, and introduces a creepy new set of monstrous aliens. It has a more complex plot than the previous episodes of the series, but everything ties together well and events are fully understandable by the end. There are also some interesting developments in the series’ arc. Overall, “Extremis” continues the high quality of Series 10 so far.