'Stranger Things' star David Harbour enjoys challenges of a hit streaming show

At the Science Museum of Minnesota on a recent morning, the live show drew the attention of most visitors. However one or two eagle-eyed people paused to stare at the tall, very bearded, man sitting among the nearby dinosaur bones doing interviews.

"I can't walk along the street and sort of not get recognized as a result of 'Stranger Things,'" David Harbour laughed.

Harbour plays Police Chief Jim Hopper in the blockbuster Netflix series "Stranger Things." It's the story set in a small Indiana town in the 1980s plagued by beasts from another dimension. Fans of the first two seasons often binged their way through the shows in a matter of hours. Season 3 launches Thursday.

Harbour explained he was at the Science Museum of Minnesota because of a sweatshirt worn by the character Dustin Henderson, a member of the show's core early-teen ensemble.

"That is actually from the 80s, from this museum," he said. "So theoretically he has been to this museum. It makes our fictional town of Hawkins, Indiana a little more, you know, grounded."

After the shirt appeared on the show fans besieged the science museum gift shop and website. That makes the museum a natural place for Harbour to talk about the show's new season, although maybe not so much about the merch.

Asked if he heard about the excitement about the shirt, Harbour was honest again. "About three minutes ago I did," he laughed.

The end of the second "Stranger Things" season and the trailer for the third hints heavily that Hawkins Indiana is in for major inter-dimensional trouble.

"We are going to end you" intones a disembodied voice. "We are going to end your friends. Then we are going to end everyone."

David Harbour claims, however, that there is a lighter tone this time round.

Each season is pegged to a holiday. The first two were Christmas and Halloween. Season 3 centers on the Fourth of July 1985.

"There is of course the, like scares, and the darkness. But in general it has kind of a summer of love feel to it, a little bit," he continued. "We let the characters spin out a little bit, the kids are growing up, the teens are going through hormonal changes, everybody is getting a little frisky. And then as the season wraps up, there's a very moving spin."

Harbour's own character, Chief Hopper, faces his own difficulties. He's now the adoptive father of the character called Eleven. She's the mysterious young woman, with devastating telekinetic powers. Eleven can kills dozens of people with a simple twist of her hands. Harbour says Hopper needs to work out how to parent such a child.

"The minute you acknowledge they have these superhuman powers, you're lost," he said. "Like how do you yell at them? How do you scold them? How do you do any of that stuff? So that's a real complex issue, and another thing going forward is how does a child like that exist in the world? And how do they grow up?"

Harbour credits the popularity of "Stranger Things" to good storytelling by the show's creators, brothers Matt and Ross Duffer. He said there's an arc to the show, building through the seasons.

"There is an end in mind," he said. "The Duffers are working with a very specific story that has an end, it's just how many hours it takes to get there."

Harbour acknowledges fans are chafing for new episodes. But he says hours of carefully constructed TV take months and sometimes years to produce.

"It's not wasted time, but it is time unfortunately," he said. "And I wish you guys didn't blow through them in two nights and then you have to wait for another year and a half. But it's the nature of the beast."

Harbour said he's grateful for how working on "Stranger Things" has allowed him to explore a character in a way unlike any other acting job, even if it also means learning the demands of working on a hit streaming show.