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'Stranger Things' Season 4: Cast, Premiere Date, Trailer, & More Info

After three seasons, Stranger Things managed to shock viewers with the latest finale. Instead of yet another set of unnerving adventures in the Upside Down, the show took a hard left and had Joyce Byers pack up her family (and Eleven) and leave Hawkins for good. On the one hand, it was such a practical solution after the heartache she suffered in losing both Bob and Hopper. On the other, it left fans wondering: Where does the show go from here? With Stranger Things Season 4 confirmed, fans are desperate to know what's next.

Season 3 gave fans many of the things they'd hoped for, including an almost-romance with Joyce and Hopper. But their potential partnership was derailed in the final episode when Hopper sacrificed himself to close the hole to the Upside Down created by the Russians under Starcourt Mall.

As Joyce, Jonathan, Will, and Eleven left town at the very end of the season, the credits rolled. But the show wasn't over. In a post-credit sequence, viewers found themselves in a Russian military base, where a new hole to the Upside Down was being tested. As the soldiers walked by a cell, they discussed "The American" inside. It seemed Hopper had survived the blast, only to be rescued out of the Upside Down USSR scientists in Kamchatka, an isolated peninsula in Russia's far east region.

It's since been confirmed that Hopper is, in fact, still alive. But that doesn't have fans any less eager to uncover deets about the new season. Here's everything we know so far:

'Stranger Things 4' Teaser

Stranger Things has released two teasers so far for Season 4, plus one "behind-the-scenes" glimpse.

The first came on Sept. 30, 2019, when Netflix announced an overarching deal with the Duffer Brothers. As part of that deal, Season 4 was a go. That being said, there wasn't much in the way of details.

The second one came on Feb. 14. Call it a love letter of sorts, the video clip showed fans that filming on the new season had begun. It also confirmed what most fans had guessed: Hopper was "The American," and life on the Kamchatka peninsula is rough.

Two weeks later, fans got a look at the cast coming together for the season's first table read. Note David Harbour's shaved head, showing filming for his scenes had already begun.

'Stranger Things 4' Cast

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Who's Back: Stranger Things has been slowly expanding the cast beyond the show's first season core of Finn Wolfhard, Gaten Matarazzo, and Caleb McLaughlin as Mike, Dustin, and Lucas. Millie Bobby Brown was supposed to only last one season as Eleven, but the writers changed their minds and kept her in the story. Noah Schnapp went from recurring actor to main cast member in Season 2 as Will Byers, which is when the show also added Sadie Sink as Max. All five stars are back for Season 4.

Also returning this season: Winona Ryder as Will's mom Joyce Byers, and Charlie Heaton as her older son Jonathan. Natalia Dyer will return as Mike's older sister, Nancy, and Cara Buono is back as their mom, Karen. Priah Ferguson was promoted to series regular for the new season, so she'll be back as Lucas' little sister Erica. Brett Gelman also got the series-regular upgrade, so Murray Bauman will be back too.

Joe Keery and Maya Hawke are also returning as BFFs Steve Harrington and Robin Buckley. And of course, as mentioned above, David Harbour is back as Chief Hopper.

New Faces: So far, the only significant addition to Season 4 is Tom Wlaschiha (Jaqen H'ghar from Game of Thrones), who will play an as-yet-unnamed Soviet soldier.

'Stranger Things 4' Plot Details

The Duffers recently posted a pile of scripts for Season 4, nine in all. Though there's no confirmed episode count, fans are taking that as a sign this season will have nine installments. As for episode titles, so far, the show has only revealed the name of the Season 4 premiere: "Chapter One: The Hellfire Club"

Beyond that, fans don't have a lot of confirmed plot details other than Hopper being alive and in Russia. But based on the show's history, there are a few things fans can count on:

Stranger Things has been covering one season per year, which means Season 4 will likely take place in 1986. That gives a twist to Hopper's being in Russia. On Saturday, April 26, 1986, the No. 4 reactor at the Chernobyl Nuclear Power Plant melted down, and it was one of the biggest disasters in modern history. How that figures into the series remains to be seen. Chernobyl is 4541 miles from the Kamchatka peninsula, but that's real-world miles. As far as the Upside Down is concerned, it could be next door.

Speaking of Hopper, actor David Harbour has given a few hints about what's to come. In an interview, he reminded fans of a scene in Season 2, in which Eleven finds boxes of Hopper's history labeled "Dad," "Vietnam," and "New York." Harbour promised those boxes were not a throwaway detail, though how Hopper's past will come into play is still a mystery.

'Stranger Things 4' Theories

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With little to go on, there aren't many theories so far. The title "The Hellfire Club" has some fans speculating about a comic book angle this season, featuring the X-Men and perhaps a plotline involving mutant powers. But so far, there's nothing to prove it one way or the other.

The most prevalent theory revolves around Hopper and how his imprisonment in Russia will play out. Based on Harbour's mention of how his character takes a dark turn this time around, fans think he might be this season's villain. Could Russia send him home to act as a sleeper agent, Manchurian Candidate style? Or could it be something worse?

When Will 'Stranger Things 4' Premiere?

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At this point, there is no date for Stranger Things 4's premiere. But fans are feeling pretty sure the show is planning a 2021 return date. As of July 6, filming is on hold due to the coronavirus pandemic. According to The Hollywood Reporter, production on the season is tentatively scheduled to resume on Sept. 17 of this year.