Multi-episode arcs are fairly commonplace on Doctor Who. During his tenure, Steven Moffat has implemented them a number of times, and, not too long ago, had an entire season made up of several smaller, multi-episode arcs. The results were mixed, to say the least. The Doctor's adventures certainly seemed more expansive on the surface, but when you looked at each arc as a whole, the result was a longer single story, not necessarily a better one. The shift back to episodic story lines, then, has afforded the series a chance to play around with its tried and true Moffatian storytelling techniques, while also ensuring that the Doctor, his companion, and the audience see much more of time and space, thanks to single-serving stories.

But now, the final season of both the series' longtime showrunner and the Peter Capaldi has introduced its first multi-episode arc, and so far it's a rather familiar one. Those telltale twisty techniques of Moffat-era of Doctor Who were on full display last week during 'Extremis', when the Doctor discovered he was inside an alien virtual reality that was running a test program ahead of a planned large-scale invasion. The hour was full of the typical narrative twists that Moffat is known for and implements on just about everything he touches, whether it be the ongoing adventures of everyone's favorite Time Lord or the world's greatest detective in Sherlock.

Now, with 'The Pyramid at the End of the World', Moffat and episode co-writer Peter Harness are prepared to dive headlong into that invasion story. Harness is an obvious choice to help with impending threat of extraterrestrials bent on world domination, as he scripted season 9's two-part 'The Zygon Invasion' and 'The Zygon Inversion', the first part of which pretty much speaks for the tone of 'Pyramid'.

Peter Capaldi and Matt Lucas in Doctor Who Season 10 Episode 7

But this isn't just any rehash of a typical Doctor Who alien invasion story line. The circumstances are similar and the stakes are as high as they usually are. And as with blockbuster films there's a yawning disconnect with those circumstances; after all, when the world is constantly at stake it becomes difficult to make those stakes seem vital. As such, in an attempt to circumvent the problem of high stakes fatigue, 'The Pyramid at the End of the World' employs some stakes of a personal nature, using the framework of a massive alien invasion by the corpse-like Monks to put the Doctor and Bill's wellbeing on the line. Again, nothing new, really, but for the ongoing thread of the Doctor's blindness and the choice that Bill makes at the end of the hour that creates a welcome consequence for her actions and the world-saving actions of the Doctor.

The series has been playing around with the Doctor's blindness for a few episodes now, and it's found a workaround in the form of the character's sonic sunglasses giving him at least a rough outline of the world around him. It's a bit of a cheat that the episode addresses by underlining the dramatic difference between a rough outline and a detailed sketch. There are hints throughout the hour, as Nardole is tasked with describing whom the Doctor is engaged with and to provide the little details his sunglasses cannot offer. Doctor Who is clearly reaching more than it usually does for dramatic effect here, but even so, the specificity of the problem brings a unique enough situation that it elevates the conflict into something other than aliens bent on world domination… for reasons.

Pearl Mackie and Matt Lucas in Doctor Who Season 10 Episode 7

Small details become the fuel that the episode runs on and which it uses to differentiate the familiarity of its plot from the other alien invasion story lines that Doctor Who has introduced over the span of its incredibly long life. The use of the Doomsday Clock conjures up fears of nuclear annihilation, thereby bringing three military super powers into play before it's discovered that a lab-grown accident caused by a hungover lab tech (played by Tony Gardner from Fresh Meat) is the genesis of the world-ending catastrophe. The hour plays with the world's militaries deciding what to do for far too long, and the idea that the officials would choose to surrender rather than go out in blaze of glory, extoling the virtues of military might is a step too far, even for Doctor Who.

Still, 'The Pyramid at the End of the World' saves its best trick for last. While not completely redeeming some of the hour's missteps, it does make a strong emotional appeal that also introduces an unexpected consequence to a decision being made by someone other than the Doctor. Faced with certain death after being locked inside the lab where the world-ending bacteria has been grown, the Doctor is saved by Bill, who gives consent of world domination to the Monks in exchange for the Doctor's sight, and the ability to save himself. It's a decent workaround to a problem the series went to certain lengths to ensure wasn't resolved with a simple deus ex machina that usually saves the day. The Doctor regaining his sight comes at a price; one that brings the hour to a close on a cliffhanger that surprisingly feels like a welcome change for the season.

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Doctor Who continues next Saturday with 'The Lie of the Land' @9pm on BBC America.

Photos: BBC America