Throughout the enthralling saga of “Stranger Things,” viewers have delved into the depths of the Upside Down, a shadowy dimension lurking beneath the fictional town of Hawkins, Indiana. This eerie underworld became etched into pop culture ever since Will Byers (Noah Schnapp) vanished into its clutches during the show’s premiere season in 2016. As we unravel the latest twist in “Chapter 7: The Bridge,” the true nature of the Upside Down is revealed. If you haven’t caught up with the episode, proceed with caution, for spoilers are imminent!

In a revelation that turns previous assumptions on their head, Dustin Henderson (Gaten Matarazzo) unveils that the Upside Down is not a mere parallel universe but a conduit bridging “space and time.” In the preceding episode, “Escape from Camazotz,” Dustin confides in Steve Harrington (Joe Keery) about his discovery of Dr. Martin Brenner’s (Matthew Modine) journals. Dr. Brenner, the erstwhile mentor to Eleven (Millie Bobby Brown) and former head of Hawkins Laboratory, penned notes indicating the Upside Down serves as a gateway that allows Vecna (a sinister character also known as Henry Creek or Mr. Whatsit, portrayed by Jamie Campbell Bower) to traverse between Hawkins and a more sinister realm teeming with malevolent entities. Contrary to past beliefs, Vecna did not create this dimension; he exploits it in his relentless quest to dominate Hawkins. With Dustin’s insights, the team gains a crucial edge in their battle against Vecna.

For fans of Dungeons & Dragons, the term “The Abyss” might ring familiar, as it denotes a chaotic evil dimension from which all malevolence originates, inhabited by demons. This reference cleverly woven into “Stranger Things” by the Duffer Brothers adds an intriguing layer to the narrative arc of the final season.

This revelation upends the foundational understanding of “Stranger Things.” The Upside Down, long thought to mirror Hawkins, is merely a transitional space to an even more terrifying world. This means the core group of heroes faces a monumental challenge ahead. Unlike the subterranean Upside Down, the Abyss floats thousands of feet above, defying previous perceptions. Fortunately, Dustin is poised to propose a strategy to tackle this newfound threat.

So how does Dustin explain what’s going on here? Let’s look at his own words, which are part of a rousing speech he delivers to the whole gang:

“We’ve always assumed the Upside Down was another dimension opened by Brenner, but it turns out it’s actually a bridge. More specifically, an interdimensional bridge that rips through space-time. It is wildly unstable but held together by exotic matter, which we found, dead center, right above the lab. In theoretical physics, they call this type of bridge a wormhole. And this wormhole connects Hawkins to here — another world, that I’ve coined the Abyss!”

This, obviously, changes almost everything we all thought we knew about the entire conceit of “Stranger Things.” If the Upside Down we’ve been seeing — the one that seems to strangely mimic the Hawkins above it — is nothing more than a passageway to something even more horrifying, it stands to reason that our central gang of Vecna fighters have their work cut out for them. Plus, the Abyss, unlike the Upside Down, isn’t under anything; it’s thousands of feet above the ground. Thankfully, Dustin seems to have a solution.

As Dustin continues to explain, he believes that the Abyss isn’t just “the true home of the Demogorgons, the vines, the Mind Flayer, [and] all the nasty sh*t from the Upside Down,” but in the moment where a young Eleven banished Henry Creel to an unknown realm, she sent him to the Abyss. Thanks to Dr. Brenner’s work with Eleven, she inadvertently “made contact with the Abyss” and, according to Dustin, “a bridge formed.” This, as Dustin puts it, is precisely how Henry, also known as Vecna, is able to constantly invade Hawkins without much of an issue: “Henry and his monsters have been using it to cross right back into Hawkins. We kicked Vecna’s ass last year but he just fled across this bridge.”

What does this mean for the fate of the Upside Down and our intrepid gang? Well, Dustin makes it clear that they can’t just blow up the Upside Down itself because then they’d blow up this bridge and fall right along with it; instead, as Vecna continues to “move” children out of Hawkins by making more and more rifts in the abyss, Steve comes up with an idea. Basically, they’ll draw Vecna closer and closer to the Abyss and blow that up with a makeshift bomb as they all escape the Upside Down together, getting rid of this dangerous bridge once and for all.

Will it work? We’ll have to wait and see when the series finale of “Stranger Things” drops. The last episode of the hit Netflix series will air on the streamer on December 31.