Will is rushed to the lab, where he cannot recognize Bob, Hopper, or Owens. Owens speculates that damaging the tunnels may be lethal to Will. He shows Hopper the lab basement, where an enormous gate to the Upside Down has been discovered under the floor.
Dart molts again and escapes the root cellar.
Nancy and Jonathan spend the night at Bauman's and admit their feelings for each other.
Lucas offers to prove to Max that his story is true, and he sneaks her out of her house. Steve, Dustin, Lucas and Max set a trap for Dart at the junkyard. Dart, now the size of a large dog, arrives with a pack of adolescent Demogorgons and traps the four in a bus.
Will announces he knows how to stop the Shadow Monster. Owens sends a team of soldiers into the tunnels, and the Demodogs leave the junkyard. Will apologizes, saying the Shadow Monster made him do it. The Demodogs ambush the soldiers, slaughter them, and climb into the lab.
This episode provides examples of:
- Absentee Actor: El doesn't appear in this episode. But she will have the next episode all to herself.
- Batter Up!: Steve once again demonstrates his dangerous efficiency with the spiked baseball bat.
- Big Damn Kiss: Nancy and Jonathan, as they finally accept their mutual attraction.
- Broken Masquerade: After giving Lucas shit about his story in the previous episode, Max now comes face-to-face with a Demogorgon and realizes it was all true.
- Can't Stop the Signal: Nancy, John, and Murray prepare the information on the Hawkins Lab and send it to various newspapers.
- Double Entendre: Bauman suspects Jonathan and Nancy are more than platonic despite their denials, so the night after they sleep at his place Bauman gets an extreme reaction from Jonathan by asking about his pull-out... bed.
- Everyone Has Standards: After Dr. Owen spends multiple episodes teetering on Ambiguously Evil, he proves to clearly be a better man than Brenner when, in a private meeting, he tells his colleagues point blank that he doesn't want Will to be harmed or killed if it can be prevented.
- Good Adultery, Bad Adultery: While they both felt like their relationship was over, Nancy had not officially broken up with Steve before she slept with Jonathan.
- If We Get Through This...: Bob mentions he wants to move to Maine with Joyce and her kids once this is over. Nice try, Bob.
- Jerkass Has a Point: The scientist who suggests burning the growth even though it will kill Will. While we're obviously not supposed to agree with him, and it sure would have been nice for them to put some actual effort into fixing Will first, he's not wrong - as far as they know, Will is going to die by the end of the day no matter what they do, so delaying the burn only serves to endanger the entire town for no purpose.
- Laser-Guided Amnesia: The Mind Flayer destroyed some of Will's memories when its tentacles were burned under the pumpkin field. Whether it did this intentionally or if it's just a side-effect of their bond is unclear.
- Let Me Get This Straight...: Steve starts with this line to recap a conversation he just had offscreen with Dustin about the latter using Dart to impress Max.
- Lured into a Trap:
- Mike realizes that the Mind Flayer used Will as its spy and the soldiers are in danger. However, he is too late to prevent the Total Party Kill.
- Steve almost becomes the victim of this when he tries to lure Dart into their own trap not knowing there are several more Demogorgons who surround him but manages to fight his way back to the bus.
- Moment Killer: Lucas and Dustin have a heart-to-heart and apologize to each other for keeping secrets, which is interrupted by Steve, who rightly points out they'll have time to talk after dealing with Dart.Steve: Hey! Dickheads! How come the only one helping me out is this random girl?
- "Not Important to This Episode" Camp: Millie Bobby Brown (Eleven) doesn't appear at all in this episode while still being listed in the opening credits.
- Ominous Fog: The scary fog at night at the scrap yard. Lampshaded by Max who calls it awesome.
- Playing Hard to Get: Steve advises Dustin that the way to attract girls is to act like you don't care. As we've seen this season, that hasn't worked out so well for him and Nancy.
- She Is Not My Girlfriend: Murray offers to let Nancy and Jonathan share his guest room, and laughs when they insist that they're not a couple. As happens with surprising frequency, he's right.
- Sherlock Scan: Bauman manages to thoroughly and accurately sum up Nancy and Jonathan's personal hangups purely from observing their behaviour.
- Shipper on Deck: Bauman thinks Nancy and Jonathan are "adorable."
- Snowy Screen of Death: Shown on the monitors of the Mission Control when the soldiers die one after the other in the tunnel.
- Spit Take: On the morning after Nancy and Jonathan sleep together, Murray Bauman asks him "how was the pull-out?". Cue the spit take from Jonathan.
- This Is Reality: Bob says to Joyce, after he is read in to what is actually happening around them, "I always thought stuff like this happened in movies and comic books."
- Total Party Kill: The entire group of soldiers sent into the Mind Flayer's tunnels are wiped out by the creatures inside.
- Trunk Shot: Of Steve pulling his baseball bat from the trunk.
- Unmanly Secret: Steve explains to Dustin how he styles his hair, which includes using women's hairspray, and threatens him never to tell anyone.
- Wham Line: "I'm sorry. He made me do it."
- Wham Shot: Steve is approaching Dart, bat in hand...when a second beast appears behind him. There were zero hints that there were more than one prior to this. And then Lucas sees a third one. And a fourth one.