The epic two-and-a-half-hour long finale of Stranger Things Season 4, "The Piggyback," is here, and if you thought the last episode, "Papa," was stressful, then you might want to sit down for this one. Let's dive right into that finale – there is a lot to unpack here.

The episode begins in Russia where our heroes (plus Yuri) are preparing for their hopeful return to America. Hop (David Harbour) and Joyce (Winona Ryder) share a long-awaited moment inside the safehouse. Joyce reminds him about that date at Enzo's they still have to get to, and Hopper says he's been dreaming about his double order of breadsticks, lasagna, and nice "Cheeanti." Joyce asks if he has been dreaming about anything else, and they (finally!) kiss. But it isn't long before they are interrupted by the phone call they've been waiting for from America. It's Dr. Owens' (Paul Reiser) right-hand agent Ellen (Paris Benjamin), who informs Hop that the Doc is "indisposed," and El (Millie Bobby Brown) and Joyce's kids "went off to fight some evil in Hawkins." Joyce comes up with a plan: the particles they saw in the prison are part of a hive mind. If they can sneak back into the prison and destroy the particles, maybe they can hurt the hive mind enough to give the kids an upper hand.

Hopper, Joyce, and Murray (Brett Gelman) set off for the prison while Antonov (Tom Wlaschiha) stays behind to ensure that come hell or high water, Yuri (Nikola Djuricko) gets Katinka off the ground. When they get to the prison, they discover that the demodogs and the shadow particles have broken out of the tanks and the guards have all been slaughtered. They learn from a just-barely-alive guard that the particles went into the demodogs, which are now wreaking havoc in the prison. Hopper comes up with a dangerous plan: lure the monsters to the pit, rain fire from above, and hope to hell it gives El and the kids an upper hand. Using himself as bait, he targets one demodog that he sees alone in the laundry room, snacking on a dead Soviet guard. Hopper whistles to get its attention and starts haul-assing it down the hallway, the demodog hot on his heels. And with that, the plan is off to a successful (and stressful) start.

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Let's move over to El and the Lenora crew, who have also figured out a way to protect Max (Sadie Sink) and the Hawkins crew from a distance. When Vecna (Jamie Campbell Bower) attacks Max, he will be in her mind. El, of course, has the same power and has entered minds before. So, she will piggyback: she will also enter Max's mind, and Max will carry her to Vecna, and then she will do some righteous mind-fighting. Yet again, Argyle (Eduardo Franco) and his commitment to his craft come in handy. He knows just where they can find a makeshift tub and 600 pounds of salt to create a sensory deprivation tank for El: Surfer Boys Pizza. And just like that, they are creating history: the first-ever mind fight held in a pizza dough freezer.

Finally, that brings us to Hawkins where the battle is just about to begin. Nancy (Natalia Dyer), Robin (Maya Hawke), Steve (Joe Keery), Dustin (Gaten Matarazzo), and Eddie (Joseph Quinn) run through the plan one more time. Phase 1: They get to the Upside Down, and Erica (Priah Ferguson) will signal Max and Lucas (Caleb McLaughlin) when they're in position. Phase 2: Max baits Vecna, which will put him in his trance in the attic of the Creel house. Phase 3: Dustin and Eddie will draw the bats away. Phase 4: Nancy, Robin, and Steve head into Vecna's newly bat-free lair, and… flambé. With Max, Lucas, and Erica already at the Creel house, Steve's crew climbs up the makeshift bedsheet rope in Eddie's trailer and into the Upside Down. Dustin and Eddie (looking simultaneously badass and adorable in their homemade battle armor) start securing the trailer, trying to make it as bat-proof as possible. At the same time, Steve, Nancy, and Robin set off for the Creel house.

Back at Surfer Boys Pizza, our California crew is also preparing for battle. Jonathan (Charlie Heaton) and Will (Noah Schnapp) are putting the finishing touches on El's salty pizza dough fridge when they share a long-overdue heart-to-heart. Jonathan sees Will watching Mike (Finn Wolfhard) and El laughing together, and the pain and longing on his face is plain as day. Jonathan apologizes to Will for being so distant (i.e, stoned) the past year. Jonathan tells Will that he doesn't want him to forget that he'll always be there for him because he loves him, "and there is nothing in this world, absolutely nothing in this world that can change that."

Back in Hawkins, Steve, Robin, and Nancy are walking through the woods trying to avoid stepping on any slithery vines and awakening the hive mind. Robin, in a panic thinking they are lost, runs ahead, leaving Steve and Nancy alone, which of course means feelings are about to ensue. That dream Steve told her about his six little nuggets? That was all true, Steve says, but he left the most important part out: Nancy is there. She's always been there. Nancy looks at him (again, barely disguised heart eyes), but before she can say anything, Robin comes running back and announces that they aren't lost -- the Creel house is just up ahead.

Meanwhile, Lucas, Max, and Erica are ready for Phase 1. Erica runs outside to the rickety jungle gym to alert Nancy, Steve, and Robin when a man walking his dog stops and takes a closer look at her. Cue collective groaning because it's the guy from the Hawkins town meeting who kicked off the town manhunt for the Hellfire club. He calls Jason (Mason Dye), the most inconvenient person in Season 4, and tips him and his goons off that he found a Hellfire club member at the murder house.

Inside the house, Lucas and Max are waiting for the signal to move to Phase 2. They are communicating via notepad when Lucas nervously shoots his shot and writes, "Movies Friday?" After a minute of serious scribbling, Max holds up her notepad to show a stick figure of the two of them holding hands in a movie theater eating popcorn. The cuteness is short-lived: Erica blinks her flashlight at them from outside, alerting them it's time to move to Phase 2: Max baits Vecna.

Max and Lucas locate Vecna using their lanterns, which means the time has come to say goodbye to Kate Bush. But for some reason, Vecna is not biting – even when Max yells, "hey, asshole!" So, Max pulls out the big guns. She sits down in front of the lantern and gives Vecna what he wants: her sorrow. She tells him that he was right – she did want Billy (Dacre Montgomery) to die, and she can't live with the guilt. "I just want you to take me away," she says, "And I want you to make me disappear." Lucas looks at her, horrified, and asks her if that's all true. "Maybe it's good he takes you," he says, his eyes turning filmy, and his voice mixing with the distorted voice of Vecna. "I'm glad it's going to be you. You will be the chosen one. The fourth. The final sacrifice. It's going to be you that breaks the world." That's the cue to move onto Phase 3: the most metal concert in the history of the world.

On top of Eddie's trailer in the Upside Down, Dustin powers up the amp and Eddie says, "Chrissy, this is for you." It's the moment we've all been waiting for as Eddie distracts the demobats away from the Creel house with his cover of Metallica's "Master of Puppets." And the distraction definitely works: the demobats come flying like literal bats out of hell and swarm the trailer, leaving Steve, Nancy, and Robin to enter the Creel house and make their way to the attic where Vecna is hanging defenseless as he attacks Max. Max manages to hide herself in her happiest memory: the Snow Ball. Now, this is where things start to really pop off… literally. Max can only hide in her happy memory for so long. The balloons in the gym start to pop, oozing with blood as the gym starts to darken. She hears Vecna's voice: "You thought you could trick me? You thought your friends could stop me? I see them. I see your friends. Just as clearly as I see you. I can feel them dying. It's time, Max."

Of course, Vecna is not the type of dude to bluff. In the Creel House in the Upside Down, the slithery tentacle vines have wrapped themselves around Steve, Nancy, and Robin, choking them. In Russia, things are also looking dire for Hop when the demodog tailing him tackles him to the ground and Hopper tries to hold its snarling mouth shut, inches from his face. And finally, Jason and his asshole buddies have arrived at the Creel house. Lucas is forced to fight off Jason, who is hellbent on making this episode even more stressful than it already is.

Back in the trailer, things are not looking so good for Eddie and Dustin either, who have taken refuge inside while the demobats swarm outside. They've done their job, but perhaps a little too well. The bats burst through the vents, and Eddie and Dustin struggle to fight them off with their spears. Dustin calls it: there are too many, and it's time to get the hell out of there. He climbs back up the bedsheet rope to the real world and calls down for Eddie. Eddie takes hold of the rope but falters. With a determined look on his face, he lets go and cuts the bedsheet. Dustin screams at him, "What are you doing?!" (Steve said no hero shit, Eddie!) Eddie straps his spear on his back and grabs his mighty trash can lid/shield and says, "Buying more time." Eddie runs outside and hops on his bike, peddling for his life and drawing the attention of the bats toward him. It isn't long before they knock him off his bike and start to swarm him, sinking their teeth into his chest.

Back inside Max's mind, Vecna appears in the gym and pins Max to the wall with his powers. He lifts his creepy claw-like hand and is about to do the thing when (triumphant music) El appears! She gains the upper hand for all of about five seconds before Vecna throws her backward through to his red soup mind world, pinning her to the detached Creel house door with tentacle vines. He carries an unconscious Max and gets ready for his second attempt. El tries to plead with him that Papa was the monster, not him, and he made Henry into what he is. Vecna/Henry/One says that Papa was just an "ordinary, mediocre man" who "sought greatness in others" like them. It was El who made him what he is when she sent him hurtling through the Upside Down.

Now, it's time for the Big Explanation. Vecna tells El: "At first, I believed you had sent me to my death. To purgatory. But I was wrong. I was somewhere new." We see the Upside Down as it once was when El first threw Henry through the gate, and it's very different from the Upside Down we know now. There are some demodogs and demogorgons in the distance, but it's more of a barren landscape. Henry continues, "I became an explorer. An explorer of a realm unspoiled by mankind … And one day, I found the most extraordinary thing of all. Something… that would change everything." This "something" Henry found are shadow particles in the sky, swirling furiously. He says, "I saw a means to realize my potential. To transcend my human form. To become the predator I was always born to be." We then see Henry stretch out his hand and begin to shape the shadows into what we now know as the Mind Flayer. Yep, that's right: it looks like Vecna/Henry/One was our Big Baddie all along.

Vecna tells her there is nothing she can do now: Hawkins will fall, and he is going to remake "this senseless, broken world" into something "beautiful." Max rises in the air once again. In the pizza shop, El is thrashing as she struggles to fight back inside Max's mind. Mike does what he should have done nine episodes ago and tells El, if she can hear him, how much he loves her. Through, yes, the power of love, El's determination grows, and she breaks free and throws Vecna/Henry/One back from Max. In Russia at the same time, Hop and team have succeeded in luring the monsters to the pit and Murray starts to rain fire from above. Vecna screams in pain, the tentacle vines release Steve and the others, and the demobats attacking Eddie fall to the ground. Steve, Nancy, and Robin realize this is their chance: it's time for Phase 4, flambé.

El is still holding Vecna back when he tells her that "this is only the beginning. The beginning of the end. You have already lost." She responds, "No. You have," and an absolute banger remix of "Running Up That Hill" cut with the Stranger Things theme song starts to kick in. In Russia, Hopper faces off against the Demogorgon (who refused to go down in Murray's flames like the others), eventually slicing his head clean off with a sword. In the attic of the Creel house, Steve, Nancy, and Robin set Vecna ablaze, as he falls, burning, through the window and outside. For a brief moment, it seems like they are victorious.

But you didn't think the Duffer Brothers would let us off that easily, did you? With everyone surviving? We all know better than that.

Dustin reaches Eddie who is lying on the ground in the Upside Down, bleeding out from his demobat wounds. Eddie smiles and says, "I didn't run away this time, right? You're gonna have to look after those little sheep for me, okay? 'Cause I'm actually going to graduate. I think it's my year, Henderson. I think it's finally my year. I love you, man." Eddie Munson, lover of heavy metal, D&D, and Dustin Henderson, is now dead.

And that brings us, finally, to Max. It turns out that El was not fast enough: Vecna released Max when El threw him backward, but she was too late. Max's limbs have already started to snap, and her eyes have already started to bleed. The fourth bell chimes and Hawkins begins to split – just like Vecna's vision – breaking the dam between the real world and the Upside Down. Max, who can't see or move, is crying in Lucas's arms that she doesn't want to die, that she isn't ready, while El sobs and holds onto her in her "darkness world." Max takes her last breath, but El is not ready to let go. She holds her hand out and places it over Max's heart, closing her eyes. The screen fades to black.

Two days later, and Hawkins is a wreck. The news reports the events as a 7.4 magnitude earthquake, "a natural disaster of unprecedented scale." The death toll is at 22, but is sure to go up with so many missing and in the hospital. Eddie Munson is widely assumed dead, but he is still the villain of Hawkins – the leader of the Hellfire cult. While Steve, Robin, and Dustin are volunteering at the high school as the town tries to recover, Dustin shares a heartbreaking moment with Eddie's uncle (Joel Stoffer), letting him know that Eddie died a hero who fought for a town that hated him.

On a more hopeful note, it looks like Robin might soon find love with a newly single Vickie, whom she runs into at the PB&J station. The Lenora gang also finally reunites with the Hawkins crew. It's mostly smiles all around, but things are clearly still tense between Nancy and Jonathan, so that's sure to be a plot point next season (I hear the shipper wars in the distance). El, Mike, and Will visit Max in the hospital, where Lucas is reading to her. It turns out that Max is alive, but she is in a coma that the doctors aren't sure she'll ever wake up from. Clinically, Lucas explains, she was dead for a whole minute, but something miraculous (cough cough, El) brought her back to life. El reaches out and touches Max's hand in the hospital bed, closing her eyes and transporting herself to her "darkness world." She calls out for Max, but what she finds is maybe even more chilling than death: nothing. There is no trace of Max anywhere. It is just pure darkness.

On a happier note, we get the reunion we've been waiting all season for between Hopper and El in their old cabin. They compare their shaved heads ("Bitchin'") and hug and cry, and for a brief moment, everything feels right in the world after the trauma that the Duffer brothers inflicted on us the past two hours. Outside, Joyce is reunited with El and her boys, and Mike and Hopper laugh and embrace. But the peace only lasts for a moment, of course. Cue sinister theme music! Will touches the back of his neck and looks up. The sky darkens as ash-like particles begin to fall. The gang walks through the woods to an open field where they see the grass has started to turn a grey-blue color, and the plants have started to wither and die. In the distance, the sky cracks with red lightning. The end has just begun.