Last week, Maeve (Thandiwe Newton) and Caleb (Aaron Paul) were dealing with a lot of problems after breaking into the newest Delos park, complete with a “Westworld massacre” Easter egg narrative for visitors. They managed to get down into the basement levels of the park and discovered the parasite inside of flies that Hale (Tessa Thompson) is using to begin to control humans, but then Caleb was swarmed by said flies. Episode 4 begins with a flashback to the end of season 3, when Maeve and Caleb blew up the supercomputer Rehoboam, and Caleb was shot. He tells Maeve that he’s sad he’ll never know life after the war, he’ll never know freedom, and she hacks his brain implants to show him memories of her own freedom with her daughter in the fields. 

The flashback is revealed to be a dream, as Caleb comes to and Hale is standing over him. “Wakey wakey,” she taunts, before informing him that she made him her pet, and intends on doing that to all of humanity, using the parasite. Caleb asks about his wife and daughter and Hale informs him that they’re “still somewhere out there alive,” but she doesn’t care because soon she’ll have everyone under her control. Every visitor to the park will be a carrier of the parasite, and they will spread it among the human population until Hale has the ability to control anyone using those weird sound waves. 

Meanwhile, Maeve and host William have a little fight, but she gets away and manages to gain control of the sound machine, overwhelming it and piercing the ears of the hosts. It eventually shatters all of the glass in the underground lab, giving Caleb a chance to get away. He grabs a shard and holds it to Hale’s throat, then Maeve shows up and they start heading for the door. They handcuff Hale, but she manages to get the sound machine working again to some degree and all of the hosts around them start going berserk. Maeve stays calm because the hosts are all copies of Westworld hosts, and she’s “lived this a thousand times.” Things seem to be going alright for the duo, then Hale manages to get into Caleb’s brain a bit and orders him to pick up a gun and aim it at Maeve. He fights her enough to not shoot, but it gives a random host opportunity to stab poor Caleb. Maeve rescues him but just barely, and they drive off into the desert in an old truck full of moonshine.

Caleb is losing a lot of blood, and he asks Maeve if she’s going to abandon him again. She explains that she didn’t abandon him after Rehoboam, but that she sat at his hospital bedside for weeks. She understood mortality for the first time, and it scared her. She realized that in order for Caleb to be free and happy, she would have to remove herself from the picture completely:

“Our kinds are locked in a perpetual struggle. I wanted you to do more than fight to survive. I wanted you to have something to fight for. I had already known the love of a daughter, and I planned on spending eternity holding it dear. I knew that if I stayed put, no harm would come to you. You deserved to have something real to hold onto. That’s why I left. And it would have been fine except one day I got curious. So I reached out through the grid to find you, and…”

And, Maeve now knows, that’s how Hale found both of them. If she had never reached out, Caleb and his family would still be safe. That has to weigh heavily on her, but they have to keep moving. They head to a construction site and unfortunately, William is waiting. (That guy just will not die.) Maeve hands Caleb her gun and he warns her not to trust him with it, but she laughs and says “I just did.” He calls his team of mercenaries to come pick them up and finds out that his wife and daughter are safe. Hale starts getting into his head and forces him to aim the gun at Maeve, but then he turns and shoots William at the last moment. The victory is short-lived, however, as William shoots Maeve from his spot lying on the ground and then gets up once more. Maeve walks over to William and wraps her arms around him, telling him that in the park she learned to “always insist on mutual satisfaction.” She has armed a bunch of explosives in the ground, and sets them off, killing both her and William.

This is where things start getting wild. We barely have a chance to grieve Maeve, one of the best characters in the series, and Hale starts questioning Caleb about his memories. We watch as Hale’s men arrive and Caleb is shot repeatedly. Hale explains that the human Caleb died that day, and that the Caleb we’re watching is a host. Not just a host, but the 278th version of Caleb that Hale has made. “It’s part of an interview, to establish a baseline. Fidelity.” We see that Caleb and Hale are in one of the rooms from the first two seasons where Dolores (Evan Rachel Wood) and her handlers would interact. It turns out that Hale’s parasite didn’t work on adults very well, so she had to wait for the next generation to become adults, all infected with the parasite as children. It’s been 23 years since Caleb died in the park. He escapes the room and is in the building where Christina (also Evan Rachel Wood) works. He runs outside and sees the Tower, then Hale makes everyone stop except her and Caleb. He realizes what that means, that the world has been lost to Hale, and it has some truly terrifying ramifications.