Last anyone saw Bill Potts (Pearl Mackie), she was handing control of the world over to the red-robed monks at the end of Doctor Who Season 10, Episode 7, “The Pyramid at the End of the World.” It certainly was the end of the world as we know it, as Episode 8, “The Lie of the Land,” opens on an Earth with an entirely different history, the monks making good on their promise to rule the Earth.

This post is one giant spoiler for Doctor Who, Season 10, Episode 8, “The Lie of the Land.” You’ve been warned.

The monks have taken over in the latest episode of Doctor Who and have changed the entire history of Earth, taking gaslighting to a whole new level. Bill knows something is wrong, but she hasn’t seen the Doctor in six months since the monks were put in charge (by her, it’s worth noting). Anyone who tries to speak the truth (that the monks only arrived six months ago and have not, in fact, been around through all of human history) is carted off and killed by the tyrannical monks.

While speaking to her mother, a purposeful figment of her imagination, Bill is interrupted by Nardole, who busts down her door and tells her he’s figured out where the Doctor is. He’s being held by the monks on a ship off the coast of the United Kingdom.

Bill and Nardole make their way to the ship, and upon finding the Doctor, Bill is horrified to find out that he’s switched sides. The Doctor is working with the monks. After a phenomenally emotional performance from Mackie, Bill shoots the Doctor with a guard’s gun. The Doctor falls to the ground, regeneration energy shooting from his hands and neck before he stands back up and starts laughing, perfectly fine.

Nardole and the guards congratulate Bill on not falling for the monks’ trick, and it turns out the Doctor was just testing Bill to make sure she hadn’t been turned herself. Of course, the Doctor would never side with the monks. He’s slowly been winning his guards over so that he now has a team of soldiers at his back.

The Doctor, Bill, and Nardole set off to try and figure out how to stop the monks and put everything back as it was. They turn to Missy for help.

After a round of back-and-forth between Missy and the Doctor, Missy reveals that she’s dealt with the monks before and that the person who gave permission to the monks to take over the world is the “lynchpin” in the plan. Render that person brain-dead, and this will all be over.

Of course, that person is Bill, and the Doctor will have none of that.

Instead of taking what he terms “the easy way out,” — killing Bill — the Doctor leads his team of guards to the pyramid first introduced in “The Pyramid at the End of the World.” That’s where the monks have a machine that’s manipulating human brainwaves so that they believe the lies the monks have been spreading. They take on the monks, sneak their way in, and lose several guards along the way. But Bill, Nardole, and the Doctor make it to the control room, where a monk that looks a bit different from the rest is hooked up to a machine and broadcasting lies.

The Doctor is incapacitated when he hooks himself up to the machine and attempts to reinsert his own memories into Earth’s history. He fails. But Bill steps up to the plate and, using the purely loving memory of her mother, breaks through the monks’ defenses and turns humanity against the monks. They leave, their giant pyramid flying away. Bill saves the Earth, proving, once again, to Who fans and the Doctor himself, that she’s a true companion and ultimately worthy of everything good that comes her way.

But the real question, it seems, for the remainder of the season will be whether or not Missy is going to turn to the “good” side. The final scene of the episode sees her crying for the people she’s killed over the years. The Doctor has been counseling her on how to be a better person. Maybe it’s working. Maybe the Doctor will finally have his friend back.

Doctor Who Season 10 airs on BBC and BBC America on Saturdays at 9 p.m. Eastern.

Photos via BBC America