Stranger Things first introduced us to the Upside Down — and blew our minds in the process — last summer. Now the Duffer Brothers' love letter to 80's sci-fi returns for its highly anticipated second season. The strange things are indeed bigger and badder than they were when we last visited Hawkins, Ind., which almost seems impossible.

To prepare for the inevitable weekend binge, here's everything you need to know about Season 2, premiering Friday, Oct. 27.

Meet the New Characters of Stranger Things

Gaten Matarazzo, Finn Wolfhard, Caleb McLaughlin and Noah Schnapp, <em>Stranger Things</em>Gaten Matarazzo, Finn Wolfhard, Caleb McLaughlin and Noah Schnapp, Stranger Things


It's Halloween 1984: This might not seem terribly important on the surface, but is a major key to not only the nostalgia factor — the kids go trick-or-treating as the Ghostbusters — but also the show's timeline. October 1984 puts us at nearly a year since Will Byers (Noah Schnapp) disappeared from the small town of Hawkins. What's been going on since we last saw everyone? You know, other than puberty. Guess we'll find out soon.

The sequel always goes bigger: The show's first season had the terrifying, nearly indestructible monster known as the Demogorgon. This season will introduce the Shadow Monster, an enormous, seemingly formless entity that's bringing the Upside Down to the human world. It's somehow linked to Will, who is seeing flashes of the Upside Down — is he experiencing PTSD or is it something more? — all around Hawkins.

The Season 2 premiere will also open in an urban setting outside of Hawkins, which means the series is now expanding and building its world in multiple ways. Basically, hold on to your butts, people.

More episodes equal a longer binge: Season 2 consists of nine episodes, which is one more episode than Season 1. What did the writers need the extra episode for? We're crossing our fingers that it's an hourlong hair tutorial; it's 1984, there are perms and mullets to be explored, man!

Stranger Things: 11 Things to Remember From Season 1

Eleven is back (and she has hair): This isn't terribly surprising news, nor is it a spoiler, because we've seen Eleven (Millie Bobby Brown) in the trailers and promotional images for Season 2. But the question of where everyone's favorite mini bada-- has been since the end of Season 1, as well as how she returns to the series, remains a mystery.

Millie Bobby Brown, <em>Stranger Things</em>Millie Bobby Brown, Stranger Things


New faces in familiar places: New cast members for Season 2 include '80s movie icon Sean Astin as Bob, a new love interest for Joyce (Winona Ryder) who runs the local RadioShack, and Paul Reiser as Dr. Owens, the new head of the nefarious lab that raised Eleven. Look for Owens and the lab to come into play when Will experiences his PTSD episodes, since you can't really take him to a regular pediatrician and hope for answers.

Elsewhere, Dacre Montgomery and Sadie Sink have joined the series as the mysterious, new-to-town step-siblings Billy and Max. The former is a bit of a jerk, and looks like the kind of guy who'd worship at the alter of The Lost Boys (yes, we know the film didn't come out until 1987). Meanwhile, Max is a tomboy who becomes friends with the boys and even catches the eye of both Lucas (Caleb McLaughlin) and Dustin (Gaten Matarazzo).

The love triangle rages on! Not even the threat of otherworldly monsters can thwart raging teenage hormones. Although Nancy (Natalia Dyer) chose Steve (Joe Keery, upped to series regular this season) at the end of Season 1, Jonathan (Charlie Heaton) isn't totally out of the picture. "At the beginning [of Season 2] Steve and Nancy have been together for like a year, which in high school is a really long time," showrunner Matt Duffer revealed to 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."

Barb's gone but not forgotten: The death of Barb (Shannon Purser) in Season 1 is still weighing on Nancy. According to Entertainment Weekly, she'll still be grappling with her best friend's death even a year later.

David Harbour, <em>Stranger Things</em>David Harbour, Stranger Things

Hopper's role as a father will come into play: "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."

Dustin gets a pet: Look, we don't know why this is important, but in an interview with EW, it was revealed Dustin has a new polliwog-like pet this season. You better believe they wouldn't reveal that if it wasn't going to come into play in some way. Let's start taking bets!

Stranger Things returns Friday, Oct. 27 on Netflix.