'Stranger Things' season 2 premiere date, cast news, spoilers: Eleven's origin story to be revealed; More time to be spent in the Upside Down

Season 2 of "Stranger Things" will dive into Eleven's (Millie Bobby Brown) origin story. Meanwhile, more of the Upside Down will be featured in the show's new season.

"Stranger Things" season 2 is set to debut on Halloween, and according to series co-creator Matt Duffer, Eleven's origin story will be one of the featured arcs.

"We do get into her story and backstory. We learn about where she came from and how she came into the world and the program that resulted in her," Matt Duffer shared with Entertainment Weekly.

Brown, who portrays Eleven, also said that her character will have "an emotional transition," which is something that they weren't able to do in season 1.

The showrunner added that although he wants the audience to know that Eleven is back, he wants to keep details of her return still a secret. In fact, they even gave Brown a codename on set to keep her storyline under wraps.

Aside from Eleven's origin story, "Stranger Things" season 2 will also dive more into the world of the Upside Down.

According to the show's composers — Kyle Dixon and Michael Stein — they will be creating "a lot more weird music" because the show will take place more in the Upside Down, Arstechnica reports.

With more time spent in the Upside Down, it is safe to say that bigger danger is coming to the town of Hawkins. Matt Duffer confirms: "In season 1, Will (Noah Schnapp) is in danger. And season 2, it's the town. The stakes escalate in that way."

One more thing that fans can expect is the return of Dr. Brenner (Matthew Modine), Screenrant reports. A previous post from Modine on Instagram hint that his character will be returning for season 2 because of the caption, "More to be revealed, uncovered." However, the post has since been taken down.

"Stranger Things" season 2 is set to premiere on Oct. 31 on Netflix.