Well, folks. It's been a long, terrifying journey, but we finally made it to "Chapter Seven: The Massacre at Hawkins Lab," the feature-length finale of Part 1 of Stranger Things Season 4. At long last, we finally learn what actually happened to El (Millie Bobby Brown) during the massacre at Hawkins Lab. But first, let's peek behind the Iron Curtain and check in on Hopper (David Harbour) to see how he's handling that Demogorgon.

In their cell awaiting their dance with the Demogorgon, Hop and Enzo's (Tom Wlaschiha) unlikely friendship is blossoming as they talk about their kids. They bond over how El and Mikhail, Enzo's son, are in the same phase of life where they are too cool for their dear old dads. Meanwhile, Joyce (Winona Ryder) and Murray's (Brett Gelman) genius plan is going off without a hitch due to Murray's A+ acting skills and flawless Russian accent. The head guard gives them a front-row seat to watch the show, and bleak recognition dawns on their faces when they hear the Demogorgon snarling and chittering behind the closed door. The buzzer goes off, and Hop and the other inmates rush to choose their weapons. Hop grabs a spear and wraps it in a rag that he immediately soaks in vodka. Unfortunately, his grand plan is off to a rough start: the Demogorgon is released and immediately starts eating people's faces, while, to his panic, Hop can't get his spear to catch fire.

Finally, Hop manages to get his spear lit. He wards off the Demogorgon while Enzo tries in vain to pry open the door. Above, Murray pulls a gun on the guard and demands that he shoot the Demogorgon, but of course, he refuses to be a traitor to his country. Murray and Joyce drag him up to the control room and tell another guard to open the door to let Hop and Enzo out. He also refuses because, as Murray says, these commies are committed, so Murray busts out his sweet karate moves and knocks them both out. Joyce promptly starts hitting all the buttons on the control panel at random, one of which opens the doors below. Enzo and Hop rush through it, but to their horror, the Demogorgon is not going down without a fight as it pries open the doors before they can close. Hop hurls the spear javelin-style into the Demogorgon's open mouth, and it screeches in rage and stumbles backward enough for the doors to close. Another door behind them opens, and Hop cautiously walks out, fists raised. He is stunned to see Joyce, who rushes forward and throws her arms around him. He looks utterly dazed for a few moments before he smiles and slowly presses his face against her head as they hold each other tight. (We're fine, there's just something in our eye.)

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Image via Netflix

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Moving over to Hawkins, a very shirtless Steve (Joe Keery) is right where we left him: thrashing around in the Upside Down as he struggles to fight off some very aggressive Demobats. Nancy (Natalia Dyer), Robin (Maya Hawke), and Eddie (Joseph Quinn) drop through the gate just in time to beat the crap out of the swarming horde using oars from the boat. Steve, freed, does something super badass, ("very Ozzy," Eddie later says), and steps on a Demobat with his bare foot and then rips it in half. Temporarily free from the flying beasts, they run into the woods to take cover before another horde swarms them. Steve, unfortunately, is a little woozy from those bat bites (and we echo Robin here – can these weird supernatural bats have rabies? Do we have to worry about Steve?!). Nancy and Steve share another, ahem, moment as she wraps his wounds. (In the distance, you can faintly hear Jonathan/Nancy shippers screeching.)

Contemplating their next move, the group decides to go to Nancy's house (you know, the creepy-crawly Upside Down version of it), where she keeps guns in her room. Steve walks with Eddie, who is getting quite the crash course on the Upside Down, or as he calls it, "Hawkins, but with monsters and nasty shit." They share an absolutely precious moment where Eddie admits he has always been a little jealous of how much Dustin (Gaten Matarazzo) looks up to Steve. He says, "Kid worships you, dude. Like, you have no idea. It's kinda annoying, to be honest." Eddie tells Steve it was very metal what he did back there with the Demobats and admits that if it weren't for the ladies jumping in first, he never would have jumped into Lover's Lake to save Steve Harrington's ass. Nancy didn't waste a second, which was, according to Eddie, "as unambiguous a sign of true love as these cynical eyes have ever seen." (Do you hear that? It's the Jonathan/Nancy shippers again. Should someone go check on them?) They arrive at the Wheeler house, where, to Nancy's confusion, her guns are not where she left them. In fact, something is way off, even for the Upside Down. She flips through her diary where the last entry is from November 6, 1983, the day Will went missing, and the gate was opened. Nancy's guns aren't here because they don't exist yet: somehow, the Upside Down is stuck in the past.

Meanwhile, Steve realizes they can hear Dustin, who is on the other side talking to Lucas (Caleb McLaughlin) and Erica (Priah Ferguson) in the Wheeler's kitchen while the police question Max (Sadie Sink) about why they were at Lover's Lake. (Office Callahan says they shouldn't have started with Max first because "she was like, kinda mean." She's so iconic.) Dustin theorizes that with each of Vecna's kills, he's not simply killing each victim: he's making a psychic connection with each victim that is powerful enough to rip a hole in the fabric of time and space. He's opening more gates to their world, and who else do they know who wants to take over their world? The Mind Flayer. If the Demogorgon was just the Mind Flayer's foot soldier, that must make Vecna his five-star general.

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As they are discussing their theory, Erica notices the light fixture in the Wheeler kitchen is flickering. On the other side, the Upside Down crew has discovered shimmery particles of light around the light fixture that they are able to touch and move around with their fingers. (Trippy.) Eddie taps the Morse Code for SOS in the particles, and Dustin realizes that yes – the Scoops Troop Elders plus Nancy and Eddie were stupid enough to go into Watergate without them. They steal little Holly Wheeler's (Anniston and Tinsley Price) Lite Brite to communicate with the Upside Down team, who tells them they are "stuck" (well, obviously). Dustin tells them their theory that there must be a gate at every murder site, so they all grab their bikes (the Upside Down team and the Hawkins-Original team) and haul-ass it to Eddie's trailer, the site of Chrissy's (Grace Van Dien) murder.

At Eddie's trailer, Dustin and the others poke a hole through that creepy-crawly crack in the ceiling and toss up a make-shift rope made out of bedsheets, which unravels down in the Upside Down, defying the laws of physics (Again, trippy.) They pull Eddie's noticeably stained mattress ("Those stains are, uh. I don't know what those stains are." Sure you don't, Eddie.) under the crack. Robin crawls up the makeshift rope and lands on the mattress, and then Eddie follows. Nancy is next, but of course, you didn't think that the whole gang would make it out unscathed, did you?

Nancy starts to climb through the gate, but instead of tumbling and landing on Eddie's stained mattress, she falls through pitch-black darkness and lands in a giant, empty concrete pool covered in vines. In the Upside Down, Steve is frantically shaking Nancy, who has gone into a trance: Vecna's curse. In Vecna's illusion, Nancy sees Barb in the pool, her body decomposing, a slimy vine slithering out of her open mouth. Blood starts to pour down the side of the pool while Nancy screams. Vecna asks her if she remembers what she did (you know, leaving Barb alone and vulnerable by the pool, the perfect snack for the Demogorgon, while she got it on with Steve in his room). When he kills someone, Vecna tells Nancy, he never forgets.

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Image via Netflix

We hate to leave you hanging on that note, but let's take a quick detour and check in on El, who is unfortunately regressing. (Our girl still can't even crush a can of Coke.) Dr. Brenner (Matthew Modine) has no other choice but to jump way ahead in the timeline and immerse El in one last memory: the massacre at Hawkins Lab. It is the morning after El's bullies attacked her in the Rainbow Room. El pretends to not remember who attacked her. Dr. Brenner tries to get a confession out of the kids, when Two, snickering with his friends, tells him that El probably fell because she's "clumsy" and "stupid." Not the brightest move on Two's part. Dr. Brenner calls him forward and puts a shock collar on him and reminds him in a horribly painful way that he is not immune to the rules. He crumbles to the floor in agony while the kids watch in horror.

Afterward in the Rainbow Room, the orderly (Jamie Campbell Bower) invites El to a game of chess. He tells her not to show any emotion as he speaks but to simply continue playing the game. He says that once Two is released from the infirmary, he and the others are going to attempt to kill Eleven. Papa will allow it to happen – in fact, he wants it to happen and has been planning it for some time now – because El frightens him. He knows she is more powerful than the others, and he won't be able to control her. That's why the security camera was cut off on the night of the attack. The orderly tells El that he is going to help her escape from the Lab today and slips her a key card under the table.

At almost 3:00 on the dot, Dr. Brenner comes into the Rainbow Room and pulls Ten out for testing (remember: this is what we saw in the first flashback scene of the season, so shit's about to go down.) El approaches the guard at the door and tells him she feels dizzy. He takes her out of the Rainbow Room and walks her to the infirmary. When he turns around, however, El is already gone, having escaped under his nose. She uses the key card and runs downstairs to the basement where she meets the orderly. He shows her a secret way out of the Lab, but tells her he can't go with her because of a tracker Dr. Brenner implanted under the skin of his neck called "Soteria." El tells him: "You help me, I help you." She uses her powers to rip the tracker right out of his neck. He picks it up and says (a little ominously, we might add), "Who knew something so small could cause so much trouble?" He thanks El, then pulls her along with him as guards suddenly burst in. They corner El and the orderly in a hallway, and the orderly tells her that she doesn't have to be afraid of them anymore. He stretches his hand out and – surprise! – he has telekinetic powers, just like Eleven. He tosses the guards like a sack of potatoes and snaps one of the guard's neck with a simple jerk of his head. He ushers El into a closet and tells her, "Like I said, we're alike, you and I." He pulls up his sleeve and reveals a "001" tattoo on the inside of his wrist, smiles, then tells her to wait there for him.

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El soon hears the sound of panicked screams and cautiously leaves the room. She sobs in horror as she sees Dr. Brenner knocked out on the floor, and the mangled, bloody bodies of the guards and the children who have been ruthlessly murdered. She goes back into the Rainbow Room where One, his white uniform now splattered with blood and his eyes bloodshot as he focuses all of his telekinetic energy on murdering a bunch of children, is not looking so friendly anymore. He turns around and sees El, standing there horrified at his wreckage. He asks why she cries for them after everything they did to her. He says, "I was scared once, too. I know what it's like to be different. To be alone in this world."

Now, this brings us back to Nancy, who has crawled out of Vecna's red soup mind world and stumbled into a very familiar memory of a young Victor Creel (Kevin L. Johnson) and his family entering their home for the first time. Only this time, the camera zooms in on little Henry Creel (Raphael Luce) Victor's son, who – surprise again! – is actually Number One. One tells El that like her, he didn't fit in with the other children. All his teachers and doctors thought that there was something broken inside him. His parents thought moving to Hawkins, a change of scenery, would do him so good. To his surprise, his new home brought about a newfound sense of purpose. Nancy watches as Henry/One finds a nest of black widows living inside a vent in the house. One tells El that he found the spiders "endlessly fascinating." Like him, spiders are deeply misunderstood, solitary creatures. They are "gods of our world" who "immobilize and feed on the weak." Humans, on the other hand, "are a unique type of pest. Multiplying and poisoning our world all while enforcing a structure of their own – a deeply unnatural structure." Where others saw order, One says, he saw a straitjacket.

One, sickened by the monotony and pointlessness of human life, realized then that he could "restore balance to a broken world," and be "a predator, but for good." (Uh, that's subjective, Henry.) Nancy watches in horror as Henry/One tortures a rabbit in the yard, snapping its bones with his mind. One tells El that as he practiced, he realized he could do more than he ever imagined. He "became an explorer" of others' memories as he reached into their minds. He says that his parents, who presented themselves as "good, normal people," were liars, just like everyone else. Nancy at this point has run back into the Creel house where she sees a baby burning alive in its cradle. One says that Victor was naive and believed it was a demon cursing them for their sins, but somehow, his mother knew and "despised" him for it. She called a doctor (we assume Dr. Brenner) to "fix" him. Of course, One says, that left him with no choice. Nancy watches as Victor's wife flies up to the ceiling, Henry/One's eyes on her. He closes them, and her bones start to snap. One says with each life he took he grew more powerful, but he was still a child and did not know his limits. He fell into a coma and woke up in the care of Dr. Brenner, who didn't want to just study him. He wanted to control him. When he realized that he couldn't control Henry/One, he tried instead to recreate him. He started a program, and others like him were soon born, like Eleven. Nancy watches as Dr. Brenner tattoos a "001" onto Henry/One's wrist.

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Image via Netflix

Eleven, at this point, is really not vibing with One's whole secret villainous backstory. Looking horrified, she tells him that he tricked her. One looks wildly offended by this accusation. He says, "Tricked you? No, I saved you. You are a prisoner here, just like me." He tells Eleven that she is superior, and that is why Dr. Brenner is so frightened of her. Together, he says, they could remake the world. He extends his hand with a smile and asks her to join him. To his shock, El says without hesitation, "No," and throws her hand out. He goes flying backward from the force of her power and crashes against the wall. They have a little telekinetic duel where it really seems like El is screwed: she is floating in the air, eyes bleeding, bones snapping (seem familiar?) when she finds strength in her memories. She remembers with fury her mother being dragged away from her, Two and the other bullies tormenting her, and all the mangled bodies of the kids One murdered. Then, the screen goes black.

But it's not over! We hear a baby crying as we are swirling around what looks like clouds of Vecna's red soup world, and see El's mother in the hospital bed, smiling and holding her as she says, "Jane, I love you." El lifts her hands and sends One crashing through the mirror and pins him against the wall. She bellows out that classic Eleven saving the world yet again scream, and One starts to disintegrate as the wall behind him begins to tear, opening up the gate to the Upside Down. Vines start to wrap around him and pull him through. He goes hurtling through the gate and into the Upside Down as red lightning strikes him repeatedly. His body starts to deform, no longer the orderly in white with the suspiciously great hair. Instead, we see him as he is now: Vecna, a vine slowly uncurling around his wrist revealing a "001" tattoo. The episode ends.

We here at Collider will see you in July for the final two, feature-length episodes of Season 4! Until then, let's all do our best to emotionally recover from that wild Part 1.