The Doctor is still blind, unfortunately. He gets a ‘message’ on his sonic sunglasses-a file called “Extremis”.
Shortly thereafter, representatives of the Vatican, including the pope, visit him, asking him to investigate a strange book, the Veritas-a book that which has driven it’s readers to suicide.
Going into the Vatican’s library, he attempts to read Veritas using a translation machine and a bit of technology, but soon finds himself attacked by bizzare corpse like “monks”. The Doctor, Bill and Nardole also discover various portals within the library leading to major world locations-but Bill and Nardole become disturbed when they can’t seem to come up with random numbers when questioned-everybody’s saying the same exact thing. All three then figure out they are in fact computer simulations, being used by the monks to plot an invasion.
However, the ‘fake’ Doctor then sends a recording of the simulation to his real self, who is sitting by the vault-and we find out who’s in it…
After his 24-year honeymoon with River Song-which ends with her being sent to the library and her final fate way back when he was the tenth Doctor, the Doctor journeys to a place where Missy is being held prisoner, presumably after she escaped from Skaro. He’s supposed to be aiding in executing her, but he only knocks her out and locks her in the vault, where he’ll keep watch over her. But now he needs her help, especially since he’s blind.
Suddenly, a giant pyramid shows up in the middle of three military zones-American, Chinese and Russian. It’s inhabited by the monks, who say that Earth will be extinct within the year, if they don’t intervene and rule over mankind. However, they don’t need to invade the regular way by force, but by asking for consent from someone. Plus they neutralize any force set against them.
Turns out this threat is a deadly virus unwittingly created by two scientists pretty much by acccident. The Doctor is able to figure this out by process of elimination, and manages to set the lab to self-destruct. Although he’s able to save one of the scientists, he himself is locked in the lab seconds before the explosion-and can’t input the key code because he’s still blind.
However, Bill, wishing to save her friend, gives the Earth over to the control of the Monks in exchange for giving the Doctor his sight back and saving his life. Unfortunately, that gives the Monks control over the planet, and using powerful hypnosis and telepathy, lead everybody to believe they’ve been in control all along, although Bill resists. The Doctor, in the meantime, broadcasts propoganda for the monks.
Bill is finally able to reach the Doctor, but it turns out he really might be working with the monks, since he feels mankind needs their help. She shoots him, and the regeneration process begins…
….but it turns out to just be a trick to make sure Bill wasn’t under their control, and the Doctor’s still the same.
Returning to the vault, the Doctor and Bill consult with Missy, who says the Monk’s signal is controlled by various statues, but Bill was the original giver of consent so she must die to break the control.
The Doctor and co try to infiltrate Monk HQ to stop the control Monk, but the Doctor’s attempt proves futile.
Bill however, manages to defeat the Monk by overpowering it with memories of her mother. The Monks then hightail it off Earth, and with their influence gone, many people forget it ever really happened in the first place. Meanwhile, the Doctor returns to Missy in the vault, and is surprised to see her remorseful.
“I keep remembering all the people I’ve killed. Every day I think of more. Being bad, being bad drowned that out. I didn’t know I even knew their names. You didn’t tell me about this bit. “
Despite her remorse, sometimes the ghosts of the past can haunt you….
Here come the drums…..