The “Stranger Things” kids are all grown up and going to war with the monsters of the Upside Down in the official trailer for Season 4.

Set to a looping version of the pulse in Journey’s “Separate Ways (Worlds Apart),” the trailer sees Mike (Finn Wolfhard), Dustin (Gaten Matarazzo), Lucas (Caleb McLaughlin) and Max (Sadie Sink) enter high school, while Eleven (Millie Bobby Brown) and Will (Noah Schnapp) are in California. As the friends navigate their different surroundings, a new supernatural threat surfaces, forcing them to once again confront the horrors of the Upside Down.

“A war is coming. Your friends in Hawkins are very much in the eye of a storm,” Eleven is warned. “I don’t know how to say this other than just to say it — without you, we can’t win this war.” Cue the title cards: “Every ending has a beginning.”

Hopper (David Harbour) is revealed to be alive, but not doing very well as he’s imprisoned in Russia and forced to fight a Demogorgon with a ragtag group of soldiers. And the final seconds of the trailer show what appears to be the big bad of the season: a human-Demogorgon hybrid that can speak.

The smash-hit Netflix series, which follows the citizens of Hawkins, Ind., as they fight against supernatural phenomena, last dropped new episodes in 2019. Season 3 ended on a series of changes for the central characters of the show, with police chief Jim Hopper (David Harbour) seemingly dying and the Byers family moving away from the town.

Filming for the fourth season initially began in early 2020, but production faced numerous delays due to the COVID-19 pandemic. Over the past year, Netflix has released various teasers for the fourth season. The first, released Feb. 14, 2020, revealed that Hopper survived the climax of Season 3 and is now alive and imprisoned in Russia. The other teasers have shown Eleven (Millie Bobbie Brown) locked up in a mental institution, several characters investigating an abandoned mansion and the Byers adjusting to life in California.

On Feb. 17, series creators Matt and Ross Duffer announced that the fourth and penultimate season of “Stranger Things” will be split into two parts. Season 4, which will consist of nine episodes, has a runtime nearly twice the length of any previous season. The Duffers did not specify how many episodes would be included in each volume, or the average length of each episode. They also confirmed that the series has been renewed for a fifth season, which will be its last.

“Stranger Things” stars a large ensemble cast, with Brown, Harbour, Wolfhard, Matarazzo, McLaughlin, Sink, Schnapp all returning from previous seasons along with Winona Ryder, Joe Keery, Natalie Dyer, Charlie Heaton, Maya Hawke, Cara Buono, Priah Ferguson and Brett Gelman. Jamie Campbell Bower, Joseph Quinn and Eduardo Franco join the cast this season. The Duffers executive produce along with Shawn Levy, Dan Cohen, Iain Paterson and Curtis Gwinn.

The first volume of “Stranger Things” Season 4 will be released May 27. The second part is set to follow on July 1.

Watch the full trailer below: