Warning: spoilers for this week's Doctor Who are in play. If you haven't seen this week's episode, come back after you have, and enjoy!
While this week's installment of Doctor Who, "Oxygen," attempted to deliver thrills and chills in space, perhaps the biggest bombshell came once the Doctor, Bill, and Nardole returned home following their adventure. After the peril that came with oxygen deprivation, courtesy of the vacuum of space, The Doctor was left temporarily blind, though it wasn't enough to prevent him from leading the charge to save the space miners that were being zombified to preserve oxygen. And just as we thought that everything was ok, with The Doctor rocking the sonic shades again, we learned something quite disturbing: Twelve's eyesight didn't actually come back as we'd previously presumed, and he's still very much blind.
Now, Doctor Who has thrown us cliffhangers that have put The Doctor in greater danger -- i.e. the Tenth Doctor seemingly appearing to regenerate after a Dalek shot him in season 4's "The Stolen Earth" -- but taking The Doctor's sight is probably the biggest shocker the series has attempted in some time, should it not just be a throwaway twist. Though much like "The Stolen Earth," "Oxygen" sees a soon-to-be outgoing Doctor suffering a crisis that some folks may think will lead to his regeneration. They might not be too off base, as one interesting detail was hidden in the first act of the episode, during The Doctor's lecture.
While discussing the various methods of death via the vacuum of space, when he was supposed to be discussing crop rotation, The Doctor drew some random diagrams on his chalkboard that formed one, cohesive picture: a human skull. This could be just a cute episode gag for the moment, but what if the image was a low-key hint that this is one of the factors that leads to the Twelfth Doctor's regeneration? The medical technology on the TARDIS surely didn't fix anything, so you kind of have to wonder how bad off a Time Lord has to be if the big blue box can't bail him out.
From a storyline perspective, though, this is small potatoes compared to Nardole's deadly serious line of questioning that started to draw the episode back to this season's through-line: the occupant of the vault that The Doctor has been protecting on Earth. More specifically, how they'd respond to any sort of weakness shown by The Doctor, as he went into a semi-monologued moment where he ultimately asked the following question:
So whatever/whoever is in the vault is obviously an adversary, which means there's a good chance The Master is being hidden in said vault. After last week's piano-playing final moments, as well as the fact that The Doctor actually interacts with this mysterious party and does so with a bit of sympathy, it's starting to feel like next week's big reveal will see the return of Michelle Gomez's Missy. But much like The Doctor at this point, we can't see exactly what's coming, so we're going to have to wait for another week of excitement and adventure, courtesy of Doctor Who. Here's hoping Twelve is able to watch along with us, through some sort of miracle or fluke.