If fans thought Stranger Things season four was jam-packed with drama and action, they’re in for an even bigger and more shocking ride in the show’s fifth and final season.

Jamie Campbell Bower, who portrays Henry Creel/Vecna in the hit Netflix series, stopped by iHeart’s I’ve Never Said This Before With Tommy DiDario and teased what audiences can expect in the show’s upcoming season.

“If you thought last season was nuts, this season is just out of control, wild, like, it’s bonkers. It really, really is,” he told the podcast host in a clip exclusively obtained by The Hollywood Reporter ahead of the episode’s release on Tuesday. “It’s bigger. It’s just completely insane. It’s completely insane.”

The actor explained that he felt like the events in the penultimate season were easy to keep track of, but this time around, he’s struggling to figure out what’s going on. He noted that the last time he portrayed a character he redid or rediscovered while filming was the role of Caius in the Twilight saga, but he got a chance to do that to some degree with Henry Creel/Vecna — with some help from the Stranger Things play in London.

The First Shadow takes place in 1959 and follows younger versions of some of the characters in the series, including Joyce Byers (Winona Ryder), Bob Newby (Sean Astin) and Jim Hopper Jr. (David Harbour). The play kicks off when new student Henry Creel moves to Hawkins, Indiana, where “his family finds that a fresh start isn’t so easy … and the shadows of the past have a very long reach,” according to the logline.

“It’s just continually building,” Bower said of Stranger Things season five. “It’s been really interesting as well to have the play on in London, which I went to go and see, which goes back to Henry before we met him in season four. And to have a lot of the questions or a lot of the thoughts that I had about that character kind of answered by watching the play and also discover more, was really interesting for me.”

The Harry Potter actor also noted there is an even higher level of detail in the show’s final installment, which excited him as an artist.

While Bower admitted they’ve filmed a lot of Stranger Things season five since production began in January, he revealed they still have a lot more to go. So, chances are, it’ll be a while before fans can experience the “wild” trip to The Upside Down for themselves.