An enigmatic title, which obviously refers to the Hellfire Club of the comics X-Men, this group of villains involved in the plot of the Dark Phoenix saga in the 1980s, including Emma Frost … In this story, the Hellfire Club was trying to seduce Jean Gray into the dark side. So if Eleven (Millie Bobby Brown) is the Jean Gray of Stranger Things, who will try to rock it? Maybe nobody. Maybe this reference to X-Men means quite another thing. We can only speculate for the moment. The filming of Season 4 of Stranger Things will take place from January 2020, which suggests an exit on Netflix in late 2020 or early 2021. You may also like.