Lucas warns Mike via walkie-talkie that government agents are en route. Mike, Dustin, and Eleven flee. Eleven telekinetically flips a van that blocks their path, and the kids escape. Lucas reconciles with Mike and Eleven.
Joyce and Hopper are called to the police station because of Jonathan's assault. Jonathan and Nancy reveal their knowledge of the monster to Joyce and Hopper. The group contacts Mike and his friends, and they rendezvous.
They ask Eleven to search for Will and Barb, but her earlier feats have left her too weak to find them. To amplify Eleven's powers, they break into the middle school and build a sensory-deprivation tank. Eleven finds Barb's corpse with a slug-like creature crawling out of her mouth. With Joyce's help, she finds Will alive, hiding in the Upside Down "Castle Byers," his backyard fort.
Hopper and Joyce break into Hawkins Laboratory but are apprehended by security guards. Nancy and Jonathan resolve to kill the monster and steal their hunting gear back from the police station.
In the Upside Down, the monster breaks into the fort where Will is hiding.
This episode provides examples of:
- Affair Hair: The Puppy Love version with Mike's mother finding a strain of the blond wig hair in the basement.
- Almost Kiss: In the opening scene, Mike and Eleven appear to be moments away from sharing a first kiss when Dustin bursts in and interrupts them. Although in Dustin's defense, it's for serious reasons, as Lucas is frantically trying to alert them that government agents are closing in on them.
- Anger Born of Worry: After learning that Jonathan and Nancy were investigating the monster, Joyce chews Jonathan out for risking both their lives to save Will, reminding him of the chance that the monster would get him, too.
- Answer Cut: When Nancy asks where they are going to get 1,500 pounds of salt, the scene cuts to them driving up to Hawkins Middle School where the de-icing salt is stored.
- A-Team Montage: A montage of the group building the sensory-deprivation tank for Eleven.
- The Atoner: After his blow-out with Tommy and Carol, Steve returns to the cinema whose marquee they defaced with Slut-Shaming graffiti and washes it off for the manager.
- Big Damn Heroes: Just as the government agents catch up to the kids, Hopper arrives and safely gets them back to the Byers house.
- Body Horror: Barbara's already dead when Eleven finds her, but the condition of her body implies that terrible things have happened. Her death itself is confirmed by a huge worm crawling out of her mouth.
- Chase Scene: In which Dr. Brenner and his agents chase after the kids.
- Crucified Hero Shot: Eleven assumes the crucified post as she floats in the home-made sensory deprivation tank.
- Defeat Means Friendship: Well, it's not friendship just yet, but getting whomped by Jonathan seems to lead Steve to a Jerkass Realization, perhaps because it brings home the fact that Jonathan's family troubles are not a joke.
- "Eureka!" Moment: Eleven gets the idea for building a sensory-deprivation tank when she sees the bathtub at the Byers' house.
- Exact Eavesdropping: Troy's mother just so happens to bring him into the police station in time for Hopper to overhear him deliver a vital clue when he needs it most — this is somewhat justified, as the events in question are all happening at the same time. Hopper would have heard about it later anyway.
- Foreshadowing: Tommy taunts Steve for "always running away", which sets up for a scene in a future episode.
- Freak Out: When Eleven sees Barb's body, she freaks out and needs to be comforted by Joyce. This shows us that, super-powered or not, she's still a kid with a very human reaction to seeing a dead body.
- Funny Background Event: When Dustin is freaking out while everyone's sitting in the bus waiting for Hopper's squad to arrive and help them, he shouts that maybe it was a trap. Lucas argues that the chief wouldn't set them up like that. Nancy, maybe, but not the chief. As Lucas says this, you can see Mike in the background look at him with a "what the hell, dude?!" sort of look.
- Heroic BSoD: Nancy has one after learning about Barb's death.
- Hollywood CB: While the kids have been using their radios realistically throughout the season, in this episode Dustin and Lucas are able to communicate while riding their bikes without having to press any buttons first on their devices.
- Immediate Self-Contradiction: Nancy and Mike agree to start being honest with each other, then instantly lie to each other about their feelings for Jonathan and Eleven, respectively.
- Instant Oracle: Just Add Water!: Played with — the sensory deprivation tank magnifies Eleven's powers and allows her to explore the Upside-Down more freely. Eleven floating in "the bath" and using her powers to find Will and Barb certainly calls to mind the image of a submerged oracle.
- Jerkass Has a Point: We're not supposed to view Troy's mother as a particularly likable woman, but it's suggested that part of the reason she's so irate is that Officer Callahan made some rather sneering comments about how her son was beaten up by a girl, which Hopper has to grudgingly concede is not cool.
- Jerk with a Heart of Gold: It becomes clear in this episode that Steve feels guilty about accusing Nancy of sleeping around, and he stands up to Tommy and Carol for their actions.
- Jump Scare: The episode ends with the Demogorgon bursting through the walls of Castle Byers.
- Just Friends: Mike and Nancy tell each other that they are just friends with Eleven and Jonathan, respectively.
- Madness Mantra: After Eleven finds Barb's dead body in the Upside-Down, she can only repeat the word "Gone!" until Joyce calms her down.
- Meaningful Echo:
- In an attempt to make up with Eleven, Lucas deliberately mentions how "awesome" it was to see the van flying over their heads when they arrive at the junkyard. This recalls Dustin's line about how awesome it was when Eleven blew Lucas across the junkyard in the previous episode.
- Mike's apology handshake to Lucas is also this. In the previous episode, while he was willing to be the first to offer the handshake due to "drawing the first blood", he was clearly sullen and grudging about it and had to be prodded into doing so by Dustin. In this episode, he offers the apology handshake first but is clearly a lot more sincere in doing so.
- Measuring the Marigolds: Played with; when Dustin calls Mr Clarke for advice on building a sensory deprivation tank, Clarke and his girlfriend are watching The Thing (1982). She's grossed out by all the Body Horror, but Clarke deconstructs the special effects by pointing out the chemistry they used to create it; however, he does so in a good-natured and interested fashion which suggests that, for him, part of the appeal of watching movies like that is to figure out how they did it.
- My God, What Have I Done?: Steve is clearly feeling somewhat guilty about what transpired between him, Nancy and Jonathan in the previous episode.
- Never Give the Captain a Straight Answer: The deputy at Hopper's office tells him that there is something he needs to see. Cut to the Trunk Shot of Jonathan's car.
- Not Now, Kiddo: Mike's mom brushes him off while talking on the phone. Right afterwards Mike brushes Dustin off, who tries to tell him that the bad men have arrived at the house.
- Obligatory Earpiece Touch: Dustin repeatedly touches his ear while talking to Lucas on CB as they dash away on their bikes in the opening scene.
- Oblivious Guilt Slinging: Joyce gives Eleven a pep talk in which she praises the girl for her bravery and support to her family but the latter is silently disgusted with herself knowing that it was her who opened the Gate in the first place. One more reason for Eleven to Must Make Amends and go into the Dark Place to locate Will and Barbara.
- Obnoxious Entitled Housewife: Mrs. Walsh, full stop. She comes in with her helmet-like Power Hair in a suit screaming that the officers weren't respectful enough to her son as they reported Eleven for breaking her son's arm and not caring whether the police department had bigger fish to fry. It's also implied she spoiled Troy and let him become the bully he is now.
- Offscreen Moment of Awesome: Hopper at the scrapyard. We don't see anything except for the first man being incapacitated, but when all is said and done, a small-town police chief neutralized three to four armed special agents in under twelve seconds.
- Planning with Props: At the scrapyard, Lucas explains where he found the lab by using branches and a tin can.
- Repeat What You Just Said: When Hopper overhears in passing Troy talk about the girl without hair:Troy: She had no hair and she was bleeding from her nose. Like a freak.Hopper: What'd you just say?Troy: I said she's a freak!Hopper: No, her hair. What'd you say about her hair?Troy: Her head's shaved.
- Run for the Border: A throwaway line by Mike to his mom.Mike: If anyone asks where I am, I've left the country.
- She Is Not My Girlfriend: Although "boyfriend" and "girlfriend" aren't used, in "The Bathtub", when the three groups join up, Mike and Nancy ask each other if they like their new opposite-sex friends. Nancy calmly denies it, while Mike is a bit more vehement about it:Nancy: Do you like Eleven?Mike: What?! Ew, no, gross!
- Shut Up, Hannibal!: Steve realizes what a pair of jerks Tommy and Carol really are and tells them to sod off.
- Silent Credits: The end credits contain no music, only the sound of the Demogorgon's breathing, considering it directly follows the Demogorgon attacking Will.
- Swiss Cheese Security: Nancy and Jonathan are able to smuggle their "monster hunting" equipment out of the police station without any guards or locked doors in their way.
- Tempting Fate: During the Chase Scene when Dustin proclaims that they might have successfully lost their pursuer, the latter immediately rush around the corner in their vans.
- Took a Level in Badass: When Mike tries to shoulder barge a locked door at the school, Nancy just casually breaks the padlock with a rock. Mike's reaction implies she's become tougher than she once was.Mike: Whoa.
- Trunk Shot: Of Hopper opening the trunk of Jonathan's car to find the bear trap and stuff.
- Unreadably Fast Text: Although it is never openly stated which government agency Connie Frazier works for, the credentials she presents to the Wheeler parents before getting agents to search their house shows she works for the NSA.
- Wait Here: Hopper decides to follow Eleven's clue and go to Will's fort in the woods by himself, but Joyce protests, so he grudgingly lets her tag along.
- Working the Same Case: The whole series has been this, but this is the episode where all the main characters finally realize that their intersecting plotlines are all converging.
- You Are Not Alone: Said by Joyce to Jonathan after she learns that he set off to solve this case alone with Nancy instead of opening up to his mother.
- You Wouldn't Believe Me If I Told You: Jonathan retorts this at Hopper when police asked about why Jonathan has so many weapons loaded in the car trunk. Hopper insists on Jonathan to try explaining anyways.