We open to Eleven brushing her teeth at Max's, I think she's starting to suspect the Mind Flayer is in Billy. Max introduces her to Wonder Woman.
At Mrs. Driscol's the paramedics are taking her to the hospital while she screams "I have to go back!" Jonathan and Nancy are understandably freaked out. The ambulance drives right by the Steel Mill, where Billy and Heather have taken her parents. Tied up and gagged, they leave the pair for the Mind Flayer in the shadows, made up of dead rats. It shoots its tentacles down their mouths, presumably to brainwash them. It's one of the most disturbing scenes in the series so far, but it's going to get a lot worse. Cue credits.
Hopper wakes up and promptly vomits. He's in a lot of pain after getting his ass handed to him by Russian Terminator. Joyce has been taking care of him throughout the night. Joyce got the license plate of Russian Terminator, she and Hopper both think it's just a State Government Agent, boy are they wrong.
The boys are trying to get in touch with the girls over the walkie talkies, they have a Code Red situation. Max isn't having it and turns off the Walkie Talkie. So, the boys call her home phone and Mike's tone of voice seems to convince Max that something is up. The boys try to reach Dustin, but he doesn't pick up because he's observing the Russians. The Scoops Troop is trying to come up with a plan to get into the room the Russians are guarding. Robin seems to have an idea, because she grabs money from the tips jar and runs off.
At the paper, Jonathan and Nancy are called into Todd's office. He's angry at Jonathan and Nancy "breaking" into Mrs. Driscol's house, apparently, she's a paranoid schizophrenic. The woman's family is threatening litigation, and Todd fires the pair.
In the Wheeler's basement, the Party goes over the facts. Will tells them about feeling the presence of the Mind Flayer. Eleven doesn't understand because she closed the gate. Will puts up the proposition that by doing so, she locked the part of the Mind Flayer that was driven out of Will last season is now locked outside in the real world with them. Max is skeptical, but Mike says "we have to assume the worst. The Mind Flayer is back." This is one of the things I love about this show. The kids are smart, and they don't fall prey to the typical horror clichés. Will explains that the Mind Flayer would want to attach itself to a new host. Eleven asks how you could tell who is a host.
Hopper and Joyce arrive at Mayor Kline's office, he starts asking questions about the Russian Terminator, having found the license plate number from Joyce. Hopper remembers seeing the guy walk out of the building. This is a nice call back to season 1, Hopper is more observant than he lets on and can immediately tell Mayor Kline is lying when he claims to not know anything. Hopper cuts out the middle-man and just starts to beat the absolute crap out of Mayor Kline until he gets some answers. Kline finally spills out that the guy works for Starcourt Mall, which has been buying up property. Hopper asks where the records are.
Nancy and Jonathan have an argument in their car, Nancy is upset because no one believes her. Jonathan is upset because he doesn't have a job anymore and doesn't have the financial stability she does (apparently Ted Wheeler makes six figures). Their argument ends with them concluding they don't understand each other anymore, and one wonders if they have broken up. It's unclear.
Back at Starcourt, Robin has managed to buy a copy of the blueprints for the Mall. It turns out the air ducts lead to the room. The problem is none of them are small enough to fit through the air ducts.
At the pool, the party observes Billy doing the lifeguard thing. Mike thinks Billy is the host and comes up with an idea. The Mind Flayer doesn't like heat, so he plans to lock Billy into the Sauna and turn the heat up, either way, they'll know if he's the host or not.
Back at the mall, Scoop Troop tries to entice the services of Erica, Lucas' bratty, obnoxious little sister because she's small enough to fit in the air ducts. Erica, being a small burgeoning capitalist, demands to be compensated for her services. Her price is free ice cream for life. For as much as Erica annoys me, I won't lie, I loved this bit.
Joyce and Hopper arrive at Kline's manor with the mayor in tow, where he gives them the deeds to the land being bought by Starcourt. Joyce and Hopper realize the property that's been bought is all near the power plant.
At the Wheeler's house, Nancy has a discussion with her Mom. She's upset about losing her job, but also angry at herself for being selfish. Karen Wheeler actually gives a very good motivational speech to Nancy, not something I would expect from the character. She encourages Nancy to finish the story.
At the pool the kids get ready to set their plan in motion. Mike tries to mend things with El, but it doesn't go well, especially when he figures out El spied on him earlier. Max really hopes Billy isn't the host, which surprised me since they seem to pretty much hate each other.
Night falls and several plots get set in motion
- Erica enters the air ducts while the Scoops Troops waits on the mall roof.
- Kline's wife arrives home to find him cuffed to the bed, he demands a phone.
- Joyce and Hopper search the properties the Mall has bought.
- Erica makes it through the air ducts and opens the door to the room.
At the pool the kids set off their plan off, luring Billy out of the showers and into the Sauna using taunts and the Walkie Talkie. The kids lock him in the Sauna and turn the heat up. Again, I love how the kids avoid the usual genre blind mistakes.
Nancy arrives at the hospital and successfully makes the bluff roll needed to see Mrs. Driscol.
Scoops Troop opens a box in a room labeled Chinese food, only to find some type of chemical container which Steve carefully removes from storage. When Steve tells everyone to step back, Dustin refuses, declaring "If you die, I die." Its oddly sweet. Suddenly the room begins to move, turns out it's a secret elevator.
Nancy takes notes on Mrs. Driscol's vitals, which start to spike. The spike is concurrent with Billy in the sauna. As we learned last season, everything from the Upside Down is connected. As the heat turns up, he gets angrier and angrier, demanding to be let out, slamming into the door. At 220 degrees he falls to the floor, crying, saying "it's not my fault Max. I've done really bad things. He made me do it." They way Billy breaks down, I don't think it's an act. For a brief moment his mind is in control, even as he grabs a broken piece of something with a shark edge. I'm not sure what it was. Will senses the Mind Flayer and Billy breaks through the window, mirroring the infamous bathroom scene from The Shining. We also get the series' first F bomb from Billy, as he threatens to "fucking gut" Max. The lights begin to flicker, and Billy's veins turn black, so does Mrs. Driscol's.
Billy breaks out of the sauna and a harrowing fight ensues. El throws a weight at him, but he throws it back at El before he grabs her by the throat and starts choking her to death. Mike hits Billy in the back of the head with a bar. It reminded me of where Finn Wolfhard hits Pennywise with a bat in It: Chapter 1, which was probably intentional. Billy backs Mike into a wall, but El manages to put him in the air before he can harm Mike. She promptly throws Billy through a brick wall before she collapses to the floor, sobbing as Mike holds her. The kids now know for certain, Billy is the Mind Flayer.
At the steel mill, Billy talks to Heather, as the camera pans back, we see several people standing still as if in a trance. In front of them the Mind Flayer grows.
This episode is intense, especially as the kids realize how much danger they're in. They also realize that, unlike the last couple of times, they can't depend on help from the adults. It can be a bitter pill to swallow, but part of growing up is learning adults can't (or won't) always protect you. The fight in the sauna makes the kids actually seem older than they actually are.