Stranger Things Season 3 shifts the story into the summer of 1985, with Hawkins transformed by the arrival of Starcourt Mall. While Mike, Eleven, Max, Lucas, Will and Dustin deal with changing friendships and teenage relationships, a much darker threat begins developing beneath the town. The Mind Flayer returns after finding a way to influence humans, eventually turning Billy Hargrove and other Hawkins residents into its controlled followers.
At the same time, Dustin, Steve, Robin and Erica discover that Russian scientists are secretly operating beneath Starcourt Mall and attempting to reopen a gateway to the Upside Down. These two storylines eventually collide during the season finale, forcing the entire group to work together. The resulting Battle of Starcourt changes Hawkins permanently, leaving one major character apparently dead and Eleven without her powers.
What Happens in Stranger Things Season 3?
The season’s central supernatural conflict begins when the Mind Flayer’s particles left behind after Season 2 find a new way to operate in Hawkins. Billy becomes its most important human servant, helping the creature gather more victims whose bodies are eventually transformed into material for a gigantic physical version of the Mind Flayer. Eleven and the others eventually realize that destroying the creature’s physical form requires closing the reopened gateway.
Meanwhile, Dustin discovers a Russian transmission and eventually learns that a secret facility exists beneath Starcourt Mall. Hopper, Joyce and Murray uncover the same operation from another direction, learning that the Russians are using a machine to reopen the Upside Down gateway. Their discoveries give the group two connected objectives: defeat the Mind Flayer and destroy the machine keeping the gateway open.
The final battle takes place at Starcourt Mall, where the teenagers attempt to hold off the Mind Flayer while Hopper, Joyce and Murray enter the underground Russian facility. Eleven is temporarily unable to fight after being injured by the creature, but she reaches Billy through memories of his childhood. Billy breaks free from the Mind Flayer’s control and sacrifices himself to protect Eleven.
Hopper and Joyce then face the machine responsible for keeping the gateway open. Hopper becomes trapped near the device, leaving Joyce with no choice but to activate it and close the gate while he appears to be killed. The Mind Flayer’s connection to Hawkins is severed, while the Russian facility is destroyed.
Three months later, Joyce, Jonathan, Will and Eleven leave Hawkins. Eleven has lost her supernatural abilities, and she believes Hopper is dead after reading the letter he had intended to give her. However, the post-credits scene reveals that a Russian prison holds an unnamed American prisoner, strongly hinting that Hopper survived and setting up the mystery of Season 4.