Season 2 is set in 1984, and is more of a sequel than continuation. There will be more scenes in the upside down world, more monsters, and additional settings.
All of the original cast is returning, including Eleven (Millie Bobby Brown) while adding two new regulars - Max and Billy. Billy (Dacre Montgomery) is a black Camaro driving bad boy and Max (Sadie Sink) is his tom boy step sister.
In the trailer we see the kids dressed up as Ghostbusters for Halloween and a clips of Eleven in captivity. We don't see much, but it's coming Halloween 2017.