Stranger Things season 4, Volume 1 is now streaming on Netflix, and while we're sure many of you will already have binged right through the seven episodes, for those who haven't, major spoilers follow from this point on.
Season 4 introduces a new big bad in the form of the murderous Vecna, and the Vol. 1 finale reveals Eleven's (Millie Bobby Brown) connection to this seemingly demonic creature as well as the rest of the Upside Down monsters we've encountered in the previous seasons.
Events kick-off in horrific fashion with a flashback to 1979, where it's strongly implied that a younger Eleven carried out a brutal massacre of her fellow test subjects in Dr. Brenner's (Matthew Modine) lab. Eleven has no memory of this, but over the course of the season she begins to feel violent urges, and when she finally stands up to bully Angela by smashing her in the face with a roller-skate, the teen psychic starts to see herself as a monster.
As it turns out, Eleven wasn't responsible for the murders at all.
When she is tricked into accompanying Dr. Owens (Paul Reiser) back to the Hawkins lab, it's revealed that Brenner is still very much alive and working on something called the Nina Project. Elle agrees to allow "Papa" to restore her powers so she can face Vecna and help her friends, and as her memories slowly return via a stint in an isolation tank, a shocking twist comes to light.
Brenner's assistant Peter (Jamie Campbell Bower), who gave advice to and mentored the younger Eleven, was actually the doctor's original test subject and Victor Creel's son. It's revealed that Brenner took him in after he killed his mother and sister, with his father believing it was the work of a demon. 001 actually killed the other kids in the lab, but Elle was able to use the full force of her abilities to open a portal to the Upside Down and banish him.
As he falls through the sky, we see 001 undergo a terrifying transformation into - you guessed it - Vecna!
We're not certain if Elle actually created The Upside Down with her vast psychic abilities or if she was simply able to access another dimension that already existed, but we're sure to find out when Stranger Things returns for its final season 4 episodes on July 1.