'Stranger Things' Season 3 Announces First New Castmembers

The world of Stranger Things is expanding.

Netflix has announced casting for two roles in the show's upcoming third season, one of whom is already a familiar face within the Upside Down universe: Priah Ferguson, who plays Erica Sinclair, Lucas' (Caleb McLaughlin) younger sister. After guest-starring in season two, Ferguson will return in season three as a recurring star.

What's more, Erica won't be alone. Netflix notes that Erica will be accompanied by "an army of friends" as she heads into the third season of the series. No longer content with sitting on the sidelines, Erica finds herself on a wild mission to save Hawkins from a dangerous and unexpected new threat.

Based on the description, it sounds like Erica and her friends will be fighting back against the Upside Down this season. If so, The Mind Flayer doesn't stand a chance.

Meanwhile, another new actor has been added to the Stranger Things cast: Maya Thurman-Hawke, who plays Jo March in BBC and Masterpiece's adaptation of Louisa May Alcott's Little Women. Thurman-Hawke will play a brand-new character, Robin, an alternative girl who is equal parts sharp and playful. Bored with her mundane day job, she just wants a little excitement in her life … and gets more than she bargained for when she uncovers a dark secret in Hawkins.

Exactly what does that dark secret entail? Appropriately enough, Stranger Things fans are very much in the dark in that regard. While the first season ended with a strong indication of the next year's story, season two ended in such a fashion that the future of the series is somewhat unknown. The Mind Flayer still towers over Hawkins from the Upside Down, but otherwise? The next moves are up in the air — exactly as the Duffers want it, according to what they previously told The Hollywood Reporter: "Last year, we had a lot of little cliff-hangers at the end of the season. We didn't want to do that again. We didn't want to box ourselves in for season three. We wanted to be able to start season three on a very clean slate."

The third season of Stranger Things is expected to land in 2019. Follow THR.com/StrangerThings for full coverage of the series.