While we anxiously wait for news of the Stranger Things Season 5 release date, Netflix has released new Stranger Things content to tide fans over. Behind the Curtain: Stranger Things The First Shadow—which began streaming on Netflix today—is a new feature-length documentary that takes viewers behind-the-scenes of the production of Stranger Things: The First Shadow, a prequel play that first opened on London’s West End in December 2023, and is now playing on Broadway.

To be clear, this film on Netflix is a “making-of” documentary, and not a taping of the Stranger Things: The First Shadow production. But it’s nevertheless an interesting watch for fans of the series, as well as fans of live theater in general. It’s not easy to put on show-stopping productions eight nights a week, and this documentary gets into the nitty-gritty of the stress, blood, sweat, and tears that goes into live theater.

Scroll down for 7 big highlights from Behind the Curtain: Stranger Things on Netflix. But first, a quick primer on Stranger Things: The First Shadow.

Stranger Things: The First Shadow is a play on West End and Broadway that is an official prequel story to the Stranger Things TV show. It’s an origin story for a young Henry Creel, before he became One-slash-Vecna.

Stranger Things: The First Shadow takes place in Hawkins in 1959, aka 24 years before the events of Stranger Things Season 1. Henry Creel—who will grow up to become Vecna, the big bad of Stranger Things 4— is a troubled teenager with a troubled family, who gets experimented on by Dr. Brenner of Hawkins Lab.

Henry goes to school in Hawkins with several familiar Stranger Things characters in their teen years, including Joyce, Jim Hopper, Bob Newby, Ted Wheeler, and more. The new documentary on Netflix takes audiences behind the scenes of the West End production, which is a great way for viewers who won’t be able to see the show on the West End or Broadway to get a taste of the show. Read on for seven big takeaways from Netflix’s Behind the Curtain: Stranger Things the First Shadow movie.

Warning: Mild spoilers for the production of Stranger Things: The First Shadow below!

1. In a Zoom call with the cast and crew of The First Shadow, the Duffer brothers revealed that director Stephen Daldry pitched the idea of a Stranger Things play “not that long after Season 1.”

   “We were like, ‘Wait, what?,'” recalls Matt Duffer. “‘What are you talking about? Like Billy Elliot’s Stephen Daldry? The Crown’s Stephen Daldry?'”

   Ross Duffer added that the creators first assumed Daldry would remake the first season as a musical. “Stephen’s like, ‘No, you morons, this is going to be a new story.'”

2. The First Shadow story was written by the Duffer Brothers, veteran Stranger Things writer and producer Kate Trefry (who has been writing on the series since Season 2), and Jack Thorne. So, yes, is this official Stranger Things canon. But more than that, the Duffers explicitly say in the documentary that fans can find hints at what’s to come in Stranger Things Season 5 by watching The First Shadow.

   “Listen, there are also some not-so-subtle hints as to what is to come, in Season 5 and beyond,” Ross Duffer says in the documentary. This quote is paired with sneak-peaks at The First Shadow script, highlighting words like “the black void,” “the rainbow room,” “transfusions,” and “the Mind Flayer.” We’re taking notes!

3. One of the leads of the show is Patty Newby (played by Ella Karuna Williams on West End and Gabrielle Nevaeh on Broadway), sister to Bob Newby. She’s a friend and love interest to a young Henry Creel, before he became a serial killing-monster guy. In the documentary, we get a sneak peek at one of Patty’s lines to Henry: “My whole life, I’ve been the girl from nowhere. The one nobody wants. But then I met you, and I swear to God, for the first time, I felt connected.”

   You’ll have to see the show if you want to know how this romance plays out, but it’s unlikely to be a happy ending for Vecna’s girlfriend.

4. While The First Shadow is mostly a Henry Creel origin story, audiences will see plenty of other familiar character names in the cast. A young Joyce, young Hopper, and young Bob Newby all have significant roles in the play. We also see appearances from Dr. Brenner, Alan Munson (father of the late, great Eddie Munson), Ted and Karen Wheeler, Lonnie Byers, Walter and Claudia Henderson (Dustin’s parents), and Charles and Sue Sinclair (Lucas’s parents).

   We get to see a few clips of the young Joyce (played by Isabella Pappas on the West End, and Alison Jaye) on Broadway, and she’s giving us drill sergeant energy as the director of a play-within-the-play. “Every scene I have, I think I’m yelling at someone, which is really fun,” Pappas says in the documentary. “It’s great. It’s very cathartic.”

5. Perhaps the most notable part of the Behind the Curtain documentary is the moment where writer Kate Trefry breaks the news to director Stephen Daldry that she just got off the phone with the Duffers, and they want to make a major cut.

   “It’s going to be 80 percent less. We’re going to be able to tell very little of the story of [bleeped out spoiler],” Trefry says, with the said spoiler censored like a curse word. “We’re going to be able to say something happened, but we’re really not going to be able to say that much. Because they want to preserve the reveal of the [bleep] for Season 5.”

   My guess? Originally, The First Shadow was going to tell us more about Dr. Brenner, but now they are saving that for Season 5 flashbacks of Papa. Matthew Modine just can’t quit this show!

6. There’s a tense moment in the documentary where writer Kate Trefry (who has been writing on the series since Season 2) scolds her collaborators for veering too far from the official Stranger Things mythology.

   “This is sci-fi, guys. This is science fiction. Not fantasy,” Trefry states, firm.

   Stranger Things isn’t fantasy? That’s news to me! Why do they keep naming guys after Dungeons and Dragons creatures, in that case?

7. Maybe I’m reading too much into it, but there’s a moment in the documentary where director Stephen Daldry pointedly sings “Sweet Dreams (Are Made of This)”—the 1983 synth pop hit from Eurythmics—to the camera. Since the play takes place in 1959, it seems unlikely that song would play a major role in The First Shadow. But Stranger Things is known for highlighting one or two ’80s songs every season. Maybe Annie Lennox is about to get that sweet, sweet Stranger Things bump.