Netflix released an intense teaser for Stranger Things that has everyone trying to find clues about season four.
It's not obvious if this season is a prequel of sorts because Matthew Modine is back as Dr. Martin Brenner aka the guy Eleven knows as Papa. He died after being attacked by a demogorgon but we never saw the body... spooky.
The teaser also has a lot of numbers so maybe they're hinting at appearances from other children/subjects pre-El.
Watch the teaser then get into some nerd theories below.