"Stranger Things 2": What to know about the second season

"Stranger Things" returns on Friday with its second season. Fans can return to Hawkins, Indiana in the '80s-inspired sci-fi show on Netflix. Here's what you need to know about "Stranger Things 2." 

It takes place on Halloween 1984. The kids of Hawkins are dressing as Ghostbusters for Halloween, and it's been a year since fans got to see them. Viewers will get to find out what's happened since Season 1. 

Season 2's monster is the Shadow Monster. Last season, the kids battled the Demogorgon, but now they'll face off against the Shadow Monster, "the big one in the sky" as actor Finn Wolfhard describes it. Like the Demogorgon, the Shadow Monster is also from the Upside Down. 

Dustin is going to get a little pet. Gaten Matarazzo told Entertainment Weekly his character will get a pollywog-like pet. "It's a little creature I get to bond with," says Matarazzo. "It's obviously not from this planet or this dimension." The "Stranger Things" Twitter account offered a sneak peek. 

The gang is back, and then some. All of the main characters will return to "Stranger Things." Eleven has hair! And the cast is growing. Sean Astin will play Bob Newby, who dates Joyce Byers (Winona Ryder). Paul Reiser plays Dr. Owens, a high-ranking official in the Department of Energy who needs to fix Dr. Brenner's (Matthew Modine) mistakes from last year. Sadie Sink plays Max, a new friend who joins the boys and Eleven. Dacre Montgomery joins the cast as Billy, Max's bad boy older stepbrother. Will Chase plays Neil Mayfield, a new father in town who is likely Billy and Max's dad. Brett Gelman plays conspiracy theorist Murray Bauman and most intriguingly, Linnea Berthelsen plays Roman, a young woman out for revenge who is not from Hawkins but is connected to the lab somehow. 

"Lucas may find his own Eleven." Caleb McLaughlin, who plays Lucas, teased on Twitter that his character will find his "own Eleven." Perhaps it means he will find his own crush, or another lab experiment escapee. 

Viewers get to learn more about Hopper's daughter. "Hopper's daughter will be the primary focus of Season 2, but not in the way that you think it will be," star David Harbour previously teased to TV Guide. "Hopper's understanding of that relationship and Hopper's understanding of being a father and of being a man grows deeper and deeper in Season 2, and we get a lot of time to explore what that is, but it won't be in the literal way that you think it is."

Nancy is still navigating a love triangle. At the beginning of "Stranger Things 2," Steve and Nancy will still be together, but showrunner Matt Duffer told TV Guide at Comic-Con, "Nancy's been dealing with some stuff — for instance, her best friend is dead. Whether Steve is the most supportive boyfriend in regard to that, we'll see. The love triangle lives on."