Netflix’s Stranger Things quickly became everyone’s favourite sci-fi show when it was released back in 2016.
The 80s-themed horror-drama series, set in Hawkins, Indiana, managed to retain its popularity through three addictive seasons.
And Netflix announced that a fourth season was on the cards in September 2019, with a simple teaser reading: “We’re not in Hawkins anymore.”
That means Millie Bobby Brown’s Eleven will perhaps return to our screens sooner than you can scream “Demogorgon”.
Here’s everything you need to know about the release date, cast and what could happen in the last series.
Warning: Stranger Things spoilers follow.
When is Stranger Things 4 coming out?
While all the Stranger Things social accounts have been active in sharing teasers, clips and hints, there’s still no official release date for season four.
Thanks to production challenges caused by the Covid pandemic, it’s possible that it may arrive even later than 2021.
In an Instagram question and answer session back in March 2020, David Harbour, who plays the beloved-but-flawed Jim Hopper in the show, said new episodes were “supposed to come out early next year”.
But in April 2021, Finn Wolfhard, who plays Mike, revealed that season four “should be out some time next year hopefully”.
That means fans of the sci-fi horror could be treated to brand new episodes in 2022. However, an exact month is yet to be announced.
We do know that the show has been in production for some time, and Mr Harbour confirmed during an appearance on Jimmy Kimmel Live in June that filming was nearly over.
"I'm almost done," he said. "I've got one more like, little stint, we should be done in like August."
What happens in the Stranger Things 4 teaser trailer?
The teaser trailer for Stranger Things 4 dropped in May this year via Netflix’s social media channels.
In the video, viewers are transported back in time to the lab where Dr Brenner conducted his experiments on children.
Everything is very spooky and echoey and there’s that industrial green-grey glow that has featured throughout all the seasons.
All the children have their heads shaved and are wearing hospital gowns, just like Eleven looked like in season one.
Dr Brenner is seen walking through the creepy, tiled corridors, before he tells the children, ominously, "Today, I have something very special planned for you".
At the same time, the camera pans to a surgical-looking door with the number 11.
The clip ends with the voice saying: "Eleven? Are you listening?" followed by a young Eleven’s eyes suddenly opening wide in shock.
What cast members will return for Stranger Things 4?
Of course, the show wouldn’t be the same without its iconic characters, and fans can expect some familiar faces to make an appearance in season four.
Eleven (Millie Bobby Brown), Mike (Finn Wolfhard), Lucas (Caleb McLaughlin), Dustin (Gaten Matarazzo), Will (Noah Schnapp), Max (Sadie Sink), Steve (Joe Keery), Nancy (Natalia Dyer), Jonathan (Charlie Heaton), Robin (Maya Hawke) and Joyce (Winona Ryder) are billed to return, among others.
And, after that shocking and emotional end to season three, we now know that Mr Harbour will be returning to play Hopper - although we still have no idea how his character survived.
Speaking to Total Film about his return, Mr Harbour intriguingly said Hopper “had to change” and “resurrect in some way”.
He said: “We'll see a very different guy going forwards. The same guy but in a different vein. It's a very cool thing to be able to play."
There will also be some new faces being revealed for season four, including Myles Truitt, who will play the role of Hawkins basketball player Patrick, and Amybeth McNulty who will play Vickie the band nerd.
Stranger Things unveiled the full list of new cast members on its Twitter feed at the start of June.
What might happen in Stranger Things season 4?
Stranger Things 4 has some major things to tie up following season three’s dramatic, 77-minute-long ending.
The final episode, titled “The Battle of Starcourt”, saw Joyce, Will and Jonathan packing up their home and leaving Hawkins with Eleven following Hopper’s apparent death.
Hence, it is likely that season four will branch outside of Hawkins.
The show’s writers, the Duffer Brothers, revealed in an interview with Entertainment Weekly that season four is “going to open up a little bit... not necessarily in terms of scale, in terms of special effects, but open up in terms of allowing plotlines into areas outside of Hawkins".
And, remember, the teaser released last September did read: "We're not in Hawkins any more.”
Netflix’s official synopsis states: “It's not all good news for our 'American'; he is imprisoned far from home in the snowy wasteland of Kamchatka, where he will face dangers both human... and other.
"Meanwhile, back in the States, a new horror is beginning to surface, something long-buried, something that connects everything..."
We also know the titles of the three first episodes of season four: The Hellfire Club, Tick Tock Mr Clock and You Snooze You Lose.
There has also been speculation that season four could be the last of Stranger Things, or if it could even be split into two halves to give fans one extra season.