Stranger Things 4: David Harbour Teases "Very Big" Hopper Reveal He Kept Secret for Five Years

It's no secret Jim Hopper survived his apparent death in Season 3 of Stranger Things, but Season 4 [...]

It's no secret Jim Hopper survived his apparent death in Season 3 of Stranger Things, but Season 4 of the Netflix series will reveal a "very big" secret that actor David Harbour has kept under wraps for five years. Stranger Things 4 pays off a set up from the Season 2 episode "Will the Wise," where Hopper's adoptive daughter Eleven (Millie Bobby Brown) discovers mysterious boxes labeled "Dad," "New York," and "Vietnam." Now the prisoner of a Russian gulag after surviving "The Battle of Starcourt" of Season 3, Hopper will "re-emerge as a different human being" with major reveals from his backstory in Stranger Things 4.

"There's some fun stuff that we're doing this season, but it's also the heaviest dramatic stuff I've ever had to do," Harbour told Entertainment Tonight. "We get to see a lot of Hopper at his most vulnerable, we're gonna reveal a lot of backstory points that we've only hinted at in boxes in his attic. We're gonna see a lot of these different threads, and also, we get to see a rebirth of him."

After playing "this guy who's struggling with his teenage daughter and sort of trapped in this world of his own darkness" in Season 3, Harbour's character is going to "re-emerge as a different human being" in Season 4.

"In that way, he has this vulnerability to him, and also this brutality that he needs to survive Russia," Harbour said. "We get to see this whole other side of him and it's some of my favorite stuff."

Stranger Things 4 brings to light a "huge" reveal about Hopper's history that Harbour has kept secret since the first season of Stranger Things released in 2016.

"There's one thing in it that plays very big in this season that I've known since the first frame of the first season. Me and [series creators] the Duffers would sit around and speculate, 'Oh, wouldn't this be cool?' the minute we started shooting," Harbour teased. "We never thought we'd even get a second season, and then we get to do it in this season. It's so satisfying to have had an idea five years prior, and to go like, 'Oh, this is a season when we're gonna let out this secret that we were using just as a subtle thing to inform something.' We're gonna lay it out finally, and it's really cool."

Netflix has not announced a release date for Season 4 of Stranger Things.