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‘Stranger Things’: What Is the Upside Down?

Originally posted on TV Insider | Last updated Dec 25, 2025 10:38 PM ET

[Warning: The below contains MAJOR spoilers for Stranger Things Season 5, Volume 2.]

Stranger Things fans are finally getting some serious answers when it comes to the origins of the Upside Down in Season 5.

In Volume 2’s “The Bridge,” it is revealed that the Upside Down is actually part of a wormhole connecting Earth and The Abyss, another dimension occupied by Vecna (Jamie Campbell Bower), the Demogorgons, Mindflayer, and more.

Dustin (Gaten Matarazzo) puts it together when he uncovers Dr. Brenner’s (Matthew Modine) notebook in the Upside Down, which undergoes a bit of a meltdown, quite literally, when Nancy (Natalia Dyer) shoots at dark matter, disrupting the stability of the space.

It seems that the Upside Down is merely a bridge connecting these dimensions, and so our heroes are setting out to end it once and for all, while destroying Vecna’s threat to meld worlds.

The wormhole revelation is an answer years in the making, as fans have wondered what the Upside Down actually is. As viewers may recall, Season 5’s Volume 1 episodes explored the idea that the Upside Down was fairly empty of creatures as Hopper (David Harbour) led crawls in the dark version of Hawkins.

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This wormhole reveal explains why it was so empty because the Demogorgons are literally otherworldly and don’t originate in the Upside Down. The biggest looming question facing fans is what was contained in the box Henry uncovered as a child.

In Max (Sadie Sink) and Holly’s (Nell Fisher) attempt to escape Camazotz, they encountered the memory that holds Vecna back from the cave. As a child, Henry crossed paths with a scientist in a desert mineshaft.

Their encounter turned violent when the man shot Henry’s hand, and in turn, Henry bashed his head in with a rock. We don’t see Henry open the briefcase, but presumably, it likely holds answers to Vecna’s true motivation.

Bower promised answers when we caught up with him for the Stranger Things Volume 2 junket, as he shared, “The way [Episode 7] ends really does set us up for 8 in a very… I just don’t think anyone’s really ready for 8. It’s very, very cool how much are we yet to explore with regards to Henry… there’s more to be discovered.”

Stranger Things, Season 5 Finale, Premiere, December 31, 2025, Netflix

This article first appeared on TV Insider and was syndicated with permission.

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