The official Stranger Things companion book, "Worlds Turned Upside Down," has confirmed that the Mind Flayer will return in season 3. The Mind Flayer has previously compared to the show's Voldemort figure, and it seems the creature still has dark designs for Hawkins, Indiana.

The Mind Flayer, also known as the Shadow Monster, was a terrifying new threat introduced in Stranger Things season 2. It's essentially the ruler of the Upside Down, and acts as the hive mind for the Demogorgons and their Demodogs. Where the Demogorgons are simply savage beasts, the Mind Flayer has a ruthless focus of its own. The end of season 2 suggested that the Mind Flayer is still out there, and has dark designs for the Earth.

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Netflix and Century Books have published the first official Stranger Things companion, "Worlds Turned Upside Down." The epilogue teases the future of the Stranger Things franchise, and it promises that the Mind Flayer will return in season 3.

The Mind Flayer hasn't lost interest in Hawkins either. The tentacled creature continues to loom near Hawkins inside the Upside Down, and its malevolent influence isn't absent from the new season. "We ended season two with a clear signal that the Shadow Monster was not eliminated, and maybe he's even identified his foe," says [producer Shawn] Levy. "And that darkness, and the battle that it will require, grows in season three."

And only a handful of kids stand between the Mind Flayer and its goal. According to "Worlds Turned Upside Down," season 3 will be set in the summer of 1985, less than a year after the events of Stranger Things season 2. But a lot has changed. Steve is a high school graduate, Mike and Eleven are officially a couple, and so are Lucas and Max. Young love has already strained the ties between the friends, "It's really the final summer of their childhood," Ross Duffer explained. "They're dealing with growing up, with these complicated new relationships. They're starting to fall apart a little bit, and maybe they don't love playing Dungeons & Dragons as much as they used to. Naturally, that's going to generate conflict."

Earlier in the book, Matt Duffer discussed that each season of Stranger Things needs to be different, needs to grow up with the central characters. "Our kids are naturally growing up and maturing," he observed. The Duffer brothers' vision for Stranger Things is that each season will be a little bit more adult, a little bit more mature. According to the Duffers, it's partly inspired by the approach J.K. Rowling took with the Harry Potter franchise.

Stranger Things has always been inspired by the classics of science fiction, fantasy, and horror. According to the Duffers, season 3 will take inspiration from John Carpenter's The Thing, David Cronenberg, and even George Romero. "There are horror movies and horror masters that we haven't really paid tribute to as much in previous seasons that we are definitely going to get into this season," Ross Duffer observed.

It sounds as though season 3 will take a darker twist, and the Mind Flayer will be central to it. At the same time, though, it's already been confirmed that there will be some sort of "new evil." Quite what this is remains a mystery; even "Worlds Turned Upside Down" doesn't give a hint. It's going to be exciting to see what comes next.

More: Stranger Things Season 3 Should Finish Filming By November

Stranger Things season 3 will stream on Netflix in 2019.