‘Doctor Who’ Regeneration Review: ‘Extremis’ Reveals What, Or Who, Is Locked Away In The Vault

The Doctor Who Regeneration Review is a weekly column cataloging all the times Peter Capaldi’s 12th Doctor nearly regenerates, or dies, in the latest episode of BBC America’s popular science fiction show. Since this is the Scottish “cross” character’s final season — a fact the showrunners have enjoyed teasing in the promos — we decided to tease back. Most items are serious, some silly, and all measured with the Doctor’s .

Aside from Pearl Mackie’s debut as Bill Potts in “The Pilot,” Doctor Who showrunner Steven Moffat has remained on the sidelines for most of this season while other writers tackled its stories. His absence has led to some intriguing plots for the 12th Doctor (Peter Capaldi), but Moffat returns in full force in the latest episode, which bears all the hallmarks of his unique — if not sometimes frustrating — style. It’s yet another horror-centric addition to Doctor Who, though Moffat does bring one of his more clever twists to it.

While the still-blind Doctor tries to appease the Vatican by investigating the Veritas, an ancient text whose interpreters all commit suicide after reading it, a periodic series of flashbacks finally reveals what he’s been keeping locked up inside that vault. It’s none other than Missy (Michelle Gomez), the current iteration of the Time Lord villain The Master, and it seems a planet inhabited by a race of executioners tasked the Doctor with her demise. As “Extremis” reveals, however, the Gallifreyan hero opts not to kill his “frenemy” and whisks her away (locked in the vault).

These flashbacks also explain the nature of the Doctor’s promise and why Nardole, who keeps reminding him about it, has been hanging around all season. In the moment prior to Missy’s decreed death, River Song’s ex-aide arrives disguised in religious garbs to remind the Doctor his deceased wife wouldn’t approve — thereby encouraging him to save Missy and hide here away in his vault instead. Unfortunately, all of this exposition kicks Mackie’s otherwise fantastic Bill to the side for most of the episode. Brief hints of her personal life pop up on occasion, but not enough to propel her ahead of the main story.

“The fatality index” ()

When “Extremis” opens, it depicts the place in which Missy’s execution will take place. Yet Moffat delays her entrance long enough for the audience to mistakenly suspect that the Doctor — and not his longtime nemesis — is being lined up for the futuristic guillotine. As one of the Rafando (Ivanno Jeremiah) explains, the device was designed specifically to cease both of his hearts and prevent any and all future regenerations from occurring. In other words, the strange platform they stand before would irrevocably end Doctor Who should its title character stand upon it.

“Will you read the Veritas” ()

Meanwhile, the main thrust of Moffat’s story involves the aforementioned Veritas text and the Roman Catholic Church’s appeal to the Doctor for help. A priest named Nicolas (Laurent Maurel), on behalf of the Pope himself (Joseph Long), implores the Time Lord to read the otherwise dangerous text in order to help them determine why so many devout clergymen killed themselves. Doing so, he explains, is a mortal sin — an act that commits all practitioners to eternal damnation without hope of grace. Intrigued, the blinded Doctor accepts the Vatican’s plea and follows Nicolas into the Haereticum to read the text.

“You gonna read this” ()

Of course, knowing the Doctor is going to read something responsible for killing countless others isn’t enough to get him killed. At least, not until he actually enters “the cage” in which the ancient book is kept. While sitting in a chair equipped with a serious of ominous restraining belts, he asks Nardole and Bill to go investigate a gunshot heard elsewhere in the library. (Another priest who read the Veritas has just committed suicide off-camera, and per his sonic sunglasses, the Doctor already knows he’s dead.) Bill suspects he’s trying to get rid of them, asking if the Doctor is actually going to read the text. He lies, “Not without you.”

“The layout is designed to confuse the uninitiated” ()

Nicolas, Bill, Nardole, the Doctor and the dead priest aren’t the only people in the secret library. The episode offers brief glimpses of what appear to be more priests clad in red robes, but there’s something different about them. Their skin appears wrinkly and old, so much so it almost looks mummy-like. The audience doesn’t get a decent glimpse of them until the Doctor uses a device to steal some eyesight from future regenerations, and the “mummy” quip isn’t that far off. They attempt to steal the Veritas, but the Doctor takes a translation and flees into the bowels of the Haereticum. The creatures almost get him, but then the scene changes.

“Turn me off” ()

The mummified priests are actually aliens preparing to invade Earth, and the Veritas is actually a manual for how to see through their strategy. Which is, as the Doctor ultimately explains to Bill and the audience, to simulate the entire planet and all life on it. Nothing save the Missy flashbacks has been real throughout “Extremis.” Everything has been a simulation, a fact the Doctor confronts head-on in the Oval Office of the White House with one of the coming invaders. He begs to be turned off and freed from the program at first, but once the clever hero realizes he can let his real-world counterpart know what’s coming, he does.

New episodes of Doctor Who air Saturdays at 9 p.m. ET/PT on BBC America.