"These are not nightmares. It's happening."
In the final episode of Stranger Things Season 1, kidnapped 12-year-old Will Byers was back at home, having escaped the parallel universe known to Hawkins, Indiana as the Upside Down. He survived a run-in with the Demogorgon… but as we learn in the final sequence of the season, once one goes upside down, he or she can never be completely rightside up again. Just when we think everything will be alright, Will coughs up a slug, a sign that he's still tethered to the monster-filled beyond.
Stranger Things Season 2 (referred to as Stranger Things 2 by creators Matt and Ross Duffer because of its sequel-like nature), picks up a year later, and despite a year's worth of promotional material for the horror-throwback series, it's still unclear exactly what Will and the other boys of Hawkins will face in their latest adventure. We've seen glimpses of a Lovecraftian cloud creature; we've seen the return of Eleven, now with an '80s-appropriate perm; we've seen more members of the Hawkins Laboratory, or if not direct employees of the facility, more government goons ready to play with otherworldly fire. What hasn't been introduced is a dramatic thrust for the season -- but a final trailer for the season gives us a taste of what to expect.