**Contains spoilers for Stranger Things season 5 Part 2**
Idk about you, but here at Cosmo HQ, we seriously binged the first drop of Stranger Things season 5.
Landing on our screens on November 26, the first four episodes of the final season had us truly gagged—and as we wait for three more episodes to drop on December 25 (followed by the finale on December 31), we're currently scrounging around for any tidbits of info that can illuminate how the show will resolve.
This sleuthing brought us to Stranger Things: The First Shadow. Already, YouTubers are sharing summary videos of the show to try and shed some light on season 5...so what is there to glean from The First Shadow?
What is Stranger Things: The First Shadow?
Stranger Things: The First Shadow is a theatrical prequel to Stranger Things, which explores the backstory of Henry Creel/Vecna.
It debuted in London's West End in 2023 and New York's Broadway in 2025.
How does Stranger Things: The First Shadow tie to Stranger Things season 5?
While this was explored in season 4, the final season of Stranger Things goes even further into Henry/Vecna's past, lore, and fears. In the latest season, Max (who is physically in a coma) is trapped in Henry's memories. However, she's able to find refuge in a cave in a desert of which Henry is "terrified." Hmmmmm!
Given that Henry is basically an evil sociopath, the fact he is afraid of a cave suggests something deeper is afoot, especially since there is not yet any explanation of this fear in the Netflix show itself. And fans of the show who have seen the theatre production The First Shadow appear to have some answers.
In the play, Henry enters a cave in Nevada on his eighth birthday and leaves without any memory of the event. The cave contains technology that is supposed to help replicate the Philadelphia Experiment, a WWII experiment that sent a battleship to another dimension.
Henry entered into contact with The Mindflayer for the first time at the cave, after which his personality and blood type changed. He also drops his spyglass in the cave, through which Brenner is able to find him for further experiments.
Where to watch Stranger Things: The First Shadow
Sadly, there are no recorded versions of Stranger Things: The First Shadow.
There is a documentary about the making of the production, however—Behind the Curtain: Stranger Things: The First Shadow—which is available on Netflix.
If you want to see the show in NYC, it's showing at The Marquis Theatre and bookings are open for December 2025 through June 2026.
Stranger Things airs on Netflix.
