'Stranger Things' Season 4 Will Reveal A "Very Big" Secret About Hopper That David Harbour Has Known Since Season 1

Last time we all saw Stranger ThingsJim Hopper, he appeared to be getting blown to smithereens inside an underground Russian scientific facility. However, unlike poor Bob (Sean Astin), Hopper survived his apparent onscreen death, appearing in a post-credit sequence that teased his continued existence. While stars Finn Wolfhard and Joe Keery have already hinted that season 4 will be the "darkest season yet", now we have some confirmation from Big Daddy Hopper himself.

Boxes in the Attic

In a recent interview with Entertainment WeeklyDavid Harbour, who portrays Sheriff Hopper on the Netflix hit, said that this season will finally dig into his many secrets.

"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 said.

Season 3 Hooper had a lot on his plate. He was trying to handle his adopted teenage daughter's first romance while still being a good dad, figure out what the Russians were doing beneath the mall, and also deal with the forces of evil coming into the town of Hawkins from the Upside Down. He survived all of that, and getting blown up, just to get taken captive by the Russians.

"[He was] this guy who's struggling with his teenage daughter and sort of trapped in this world of his own darkness, [...] he's going to re-emerge as a different human being," Harbour said. "In that way, he has this vulnerability to him, and also this brutality that he needs to survive Russia. We get to see this whole other side of him and it's some of my favorite stuff."

Part of getting to see that other side of him is a reveal that has been building since season 1, Harbour hinted.

"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."

The "boxes in the attic" Harbour refers to are from the season 2 episode "Will the Wise." While cleaning out their shared cabin, his adoptive daughter Eleven (Millie Bobby Brown) discovers mysterious boxes labeled "Dad," "New York," "Vietnam," and "Hawkins Lab" in a hidden cellar. (Attic, cellar, same difference right?) Eleven grabbed the Hawkins Lab box and gave us all a peek inside, but the contents of the other three boxes are still a mystery.

A Long-Held Secret

In addition to whatever secrets are hinted at in those boxes, we'll apparently also be getting a major reveal about Hopper's history. Harbour and series creators the Duffer Brothers apparently have known since the very first season released in 2016, and he's thrilled to get a chance to share it.

"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 the Duffers would sit around and speculate, 'Oh, wouldn't this be cool?' the minute we started shooting. 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."

To find out Hopper's big secret, you'll have to watch season 4 of Stranger Things. Netflix has not announced a release date yet, but you can always watch seasons 1-3 again to try and figure out exactly what he's going on about. Good luck!