An army of Demodogs erupts out of the tunnels and begin breaking through into the rest of the Hawkins Lab. Those on the inside — Mike, Joyce, Hopper, Bob, and Doctor Owens — realize that the creatures are homing in on Will, and Joyce sedates him to throw them off.
A catastrophic systems failure leads to them being trapped in a security office on the upper floors when the power goes out, with the creatures having free run of the facility. Bob, being more technologically adept than Hopper, volunteers to go out and restart the necessary systems to restore power. Owens stays behind and uses the security cameras to guide the others out. Mike, Will, Joyce, and Hopper escape, but Bob is killed by the Demodogs.
The group retreat to the Byers' house, where Dustin suggests that the Shadow Monster is a Mind Flayer. After disguising their location, they interrogate Will. Using Morse code, he taps out, "CLOSE GATE." The house phone rings, and Will realizes where he is. The Mind Flayer sends a Demodog to the house, but Eleven arrives and kills it.
This episode provides examples of:
- A-Team Montage: The whole cast joins to prepare the tool shed for Will.
- Abusive Parents: This episode finally gives a little more detail as to why Billy is so angry all the time: his father, Neil Hargrove, is a violent authoritarian who thinks nothing of slapping his son around.
- All Germans Are Nazis: Steve seems to assume this:Dustin: [about the Mind-Flayer] It believes it's the "master race".Steve: Like the Germans.Dustin: [offended] Uh, the Nazis?Steve: [embarrassed] Yeah- yeah, the Nazis.
- Always a Bigger Fish: Neil Hargrove out-assholes his son Billy.
- Answer Cut: When Jonathan and Nancy meet up with Dustin, Lucas, Max and Steve outside Hawkins Lab.Dustin: They're not in there, are they?Nancy: We're not sure.Jonathan: Why?Demodogs: *roaring from inside the lab*
- Antagonist Title: Named for the nickname Dustin applies to the shadow monster, taken from the D&D Monster Manual.
- Bait-and-Switch: As Jonathan and Nancy are trying to get past the lab's front gate, they see flashlights approaching from the trees, and think it's security officers patrolling. It turns out to just be Steve with Dustin, Lucas and Max.
- Behind the Black: Bob thinks he's home-free after arriving in the lobby... only for a Demodog to suddenly pounce from offscreen. There was no indication it was there, nor did anyone notice until it struck. He ends up dying and Joyce and Hopper are forced to abandon him when the other Demodogs burst through.
- Big Damn Heroes: As the group prepares for a last stand at the Byers house, Eleven arrives and drives off the attacking Demodogs, killing at least one of them.
- Big Damn Reunion: The episode ends with the beginning of Mike and Eleven's reunion. Once his brain finally processes that Eleven is really standing in front of him, Mike breaks out the biggest grin of his life.
- Call-Back:
- The demodogs are seen mauling Hawkins lab personnel in a failed Elevator Escape moment which recalls the very first scene of Season 1 where a lab assistant is killed in the elevator by the Demogorgon.
- To help jog Will's memory, Jonathan plays the first mixtape he made for Will to drown out an argument their parents were having. The first song on the tape? "Should I Stay Or Should I Go?", which Will was able to transmit out of the Upside-Down back in Season 1. Also, when Hopper asks if Jonathan can use Lonnie's old rifle, Jonathan (knowing he's a terrible shot) hesitates, and Nancy steps in to say she can use it.
- Calling Parents by Their Name: When his parents get home at the beginning, Billy refers to his stepmother as "Susan".
- The Cavalry: Hopper requests police support via phone call. Nobody of the group actually believes this is gonna happen. It's not, but there's still a badass friend out there to save the day.
- Come with Me If You Want to Live: Jonathan arrives at the lab in his car to pick up the survivors before the demodogs can break through the barred front door.
- Cooldown Hug: Hopper gives one to Will when the latter trembles in agony at the shed.
- Correlation/Causation Gag: While the lab's power is out, preventing anyone from opening the security gate, Dustin keeps hitting the button in the guard station. He keeps it up until Bob gets the power on and unlocks the door, making Dustin think his Button Mashing worked.
- Crouching Moron, Hidden Badass: Dad joke-loving bumbling Nice Guy Bob not only puts his technical abilities to the test by hacking into the lab's computer system to restore it's electricity, but does so while evading literal monsters and staying (reasonably) calm throughout. Too bad he pauses long enough for one of them to take him down.
- Curiosity Killed the Cast: To be new to the situation, Max lampshades this when the others rush to locate the source of the Demodog howling.Dustin, Lucas & Steve: *run off toward the sounds of Demodogs*Max: N-n-no, hey, hey guys, why are you headed toward the sound?! Hello?! Helloooo?! Shit!
- A Death in the Limelight: Bob gets a lot of focus in this episode. Half way through you learn why.
- Death Is Dramatic: Bob's death scene is played in slow motion accompanied by a Futile Hand Reach and a Big "NO!" from Joyce.
- Devoured by the Horde: This happens to Bob after the demodogs got him.
- Door Handle Scare: Used suspensefully in the scene where the heroes are under attack from the demo-dogs and suddenly the door starts opening. Turns out it's Eleven entering.
- Due to the Dead: In the wake of Bob's death, Mike praises him as the person who not only was responsible for starting Hawkins Middle School's Audio-Visual Club, but that he taught their science teacher Mr. Clarke everything Clarke knows about AV technology.
- The End of the World as We Know It: Lucas reminds everyone that this trope is about to happen if they cannot stop the Alien Invasion.
- Escaped from the Lab: The demodogs manage to break out of the facility and start roaming the area.
- "Eureka!" Moment: Mike has one when somebody mentions the word "army" which makes him think of the demodogs as being a Keystone Army.
- Everybody's Dead, Dave: Hopper, Owens, Joyce and Mike have a Mass "Oh, Crap!" moment when they look on the security monitors and realize that they're the only ones left alive in the building.
- Everyone Knows Morse: Will communicates to his friends this way, and they are able to translate it. Justified as Hopper is the one transmitting the pulses, while Dustin, Lucas and Nancy team up to write them down and look up the letters from a decoder chart. Also serves as a Call-Back to Hopper teaching Morse to El as a way to communicate with her while he's at work. Also justified for the boys, as incredibly nerdy members of the AV club. Steve, however, does not know Morse, and is the only one not to recognise the communication as such.
- Facepalm: Hopper's reaction when Dustin is explaining the Mindflayer from the Dungeons & Dragons manual. His expression as he does so just screams "What has my life become?".
- Feet-First Introduction: When the door opens in the closing scene, the camera hovers above ground showing only the shoes of the person entering. In slow motion for added effect. Then reveals it's Eleven.
- Fighting from the Inside: The Mind Flayer retains control over Will's conscious mind and so he can't verbally tell the others how to stop the Mind Flayer, but he can tell them them how to fight it by tapping out a message in Morse Code: C L O S E G A T E.
- Freudian Excuse: Seeing Billy's father reveals a lot about what his problem is.
- Heroic Sacrifice:
- Bob goes down to restart the computer to unlock the doors. He almost manages to make it out in time before a Demodog pounces him.
- Dr. Owens offers to stay behind at the lab's control room and guide Hopper, Joyce, Mike, and Bob out of danger. The episode ends before we learn his fate.
- Hive Mind: Dustin compares the Shadow Monster's control over Will and the Demodogs to this, just as Owens did about the "virus" he told Joyce and Hopper about several episodes prior.
- Hollywood Hacking: When Bob brute-force hacks the computer system at the lab, we're shown the actual BASIC script he uses to acquire the password - which probably damages more believably than the specifics remaining off-camera. details
- Hope Spot: Bob makes it to the server room and restarts the power and opens all the doors. He makes it past a demodog in the hallway. He makes it to the lobby and manages to close the door behind him. He and Joyce say hi. Then a demodog comes in and no more Bob.
- Hypocrite: One of Neil Hargrove's many, many flaws. Threateningly, he reminds Billy about showing "respect and responsibility", when he clearly has no respect whatsoever for Billy, and just moments after arriving home hours later than he was due and blaming Max's disappearance on Billy.
- Hypocritical Humor: Dustin berates Lucas for correcting him about using the word metaphor instead of analogy, but then goes on to correct Nancy when she says Mind Flamer instead of Mind Flayer.
- "I Know You Are in There Somewhere" Fight: Joyce and others share heartwarming anecdotes with Will to revert his fading sense identity and encourage him to start Fighting from the Inside. It works. Not directly, but it works.
- Internal Reveal: While Eleven at least met most of the people in the Byers house, Hopper is the only person who knew that she didn't die at the end of the first season. When she walks in everyone else is stunned, but the look of pure happiness on Mike's face is quite touching.
- Jaw Drop: Nancy, Dustin, Lucas, Max, and Mike have this reaction to seeing Eleven alive, though Mike's mouth eventually turns into the biggest smile of his life when he finally processes Eleven is standing in front of him.
- Jerkass: Billy's abusive father fits this trope even more than his son does.
- Jerkass Ball: Owing to his misery over Eleven, Mike is still treating Max like an enemy, despite the fact that she's now a Secret-Keeper.
- Keystone Army: Discussed. Mike suggests that stopping the Mind Flayer may also stop its Demodog army.
- Let's Get Out of Here: Dr. Owens tells Bob to get out of there!
- Logical Weakness: The main strength of the possessed Will, him being able to transmit his surroundings for the Mind Flayer to send its forces to, is also a weakness. As Mike explains, he's a spy, but he can't do his job well if he doesn't recognize where he is. Hence, they put him in the shed, so that it's far less likely for him to know where is, and thus, keep the Mind Flayer from homing in on him.
- Metaphorgotten: Dustin's description of the Mind Flayer that possessed Will and his referral to the Mind Flayer in the D&D game falls apart when he says that using fire is a bad idea (when the Mind Flayer has already been established as being weak to heat) and suggests using an army of zombies to kill it.
- Offscreen Moment of Awesome: The audience doesn't see what Eleven did to kill one Demodog and drive off the others, but it sure sounded pretty awesome.
- O.O.C. Is Serious Business:
- After having her son possessed and her boyfriend killed, Joyce drops her usual mild-mannered demeanour and says out loud that she wants to kill the Mind Flayer.
- The normally confident and aggressive Billy becomes noticeably submissive and afraid when his abusive father starts getting physical.
- Overcrank: Bob's death is filmed in slow-motion to emphasize the scene's heavy emotional impact.
- Perp Sweating: Will gets tied up and has several portable work lamps pointed at his face in order to disorient him.
- Plot-Demanded Manual Mode: After the lab goes into emergency shut down, locking the heroes in with the demodogs, Bob has to reach the basement to override the security codes with a manual input that will open the gates for the group to escape.
- Point That Somewhere Else: Hopper shows Bob how to use a handgun but doesn't give him any safety instructions other than showing him the safety. When Bob inevitably points the gun at Hopper, he just gently pushes it away.
- Politically Incorrect Villain: Neil Hargrove casually drops a few bigoted slurs into his dialogue while abusively "teaching respect" to his asshole son. Most notably, he calls Billy's date "whore" when casually telling him to call it off so he can find Max.
- Punctuated! For! Emphasis!: Billy's agitated dad slams him into a wall, backhands him, and asks slowly "What. Did. We. Talk. About?"
- Rapid-Fire Typing: Bob types out his BASIC code at breakneck speed.
- Red Shirt Army: The Hawkins Lab soldiers are slaughtered en masse, yet again. You'd think the fact that Jonathan, Nancy and Steve could all have told them bullets don't work very well might have come up when they were debriefed the previous year.
- Slow Electricity: When the power cut occurs at Hawkins Lab, the lights go out floor by floor. Justified, as high-security facilities are often wired in such a way that each floor is on its own power. It's later shown that Bob has to reset several series of breakers.
- So Much for Stealth: When Owens tries to guide Bob out of a Demodog-infested lab by having him quietly sneak around, it looks like Bob successfully evades one of the Demodogs by hiding in a storeroom...only for a mop to fall over right next to him, alarming said creature of Bob's presence and forcing Owens to change his plan to a single step: "Run!"
- Take a Moment to Catch Your Death: Played straight as an arrow with Bob's death. After being chased down corridors by Demodogs, Bob arrives at the lab's lobby which seems to provide safety. He takes a deep breath and shares a loving look with Joyce. Cue a Demodog attacking him from Behind the Black.
- Tempting Fate: When a Demodog begins banging against the glass door, Owens reassures Hopper that the creature can't get through. Cue several more swarming out and starting to break the glass.Owens: It's polycarbonate. It can't get through.
(Cue more Demodogs coming up causing cracks in the glass)
Hopper: You sure about that glass?
Owens: (hits the alarm) - This Is Reality: Hopper points this out when the boys try to figure out the Mind Flayer using their D&D manual. While it has helped them in the past, Dustin comes to agree when he gets to the part about the zombie army.
- This Way to Certain Death: On his way to the basement Bob encounters several mutilated corpses.
- Trapped-with-Monster Plot: This episode has the heroes trapped inside the Demodog-infested lab.
- Voice of the Legion: When Will comes to in the storage shed, he quickly begins to fight his restraints, repeatedly screaming "Let me go!" Midway through, his voice combines with a deeper, flanged one.
- We've Got Company: Said by Dr. Owens when he notices demodogs coming Bob's way as the latter tries to make it back to the rest of the team.
- Workplace-Acquired Abilities: Bob's knowledge of BASIC comes in handy when escaping from the lab requires an override of the security codes with a manual input.
- Wrong Genre Savvy: Bob ensures Joyce that he is gonna make it through his Heroic Sacrifice just fine because he is "Bob Newby, superhero". However, as it turns out he doesn't have enough Plot Armor and winds up as a Sacrificial Lion for the show.
