Season synopsis
Contains spoilers for this season and earlier seasons.
In 1987, a military quarantine has closed Hawkins after the rifts opened, and the friends make “crawls” into the Upside Down to find Vecna. A Demogorgon attacks the Wheeler home and takes Holly, Mike and Nancy’s younger sister, into Vecna’s mindscape, where he appears to her as the kindly Mr. Whatsit. Max is also trapped there, hidden in a cave inside Henry Creel’s memories; she and Holly find each other and plan an escape. Joyce and the others try to protect Derek, while Eleven and Hopper search the military base as Dr. Kay hunts Eleven.
At the end of the first volume, Will turns his link to Vecna against him, lifting and breaking the Demogorgons that attack his friends. Eleven and Hopper discover the captive is Kali, Eleven’s sister, not Vecna. Max and Holly escape Henry’s mind. Dustin works out that the Upside Down is a wormhole connecting Hawkins to the Abyss, while Vecna uses twelve kidnapped children to pull the two worlds together. The group enters the Abyss to rescue them; Eleven, Kali and Max confront Henry in his mind.
The final battle reveals the Pain Tree is the Mind Flayer. Nancy draws the creature toward a canyon while the others attack it with fire, explosives and spears; Will helps Eleven hold Vecna long enough for her to impale him, and Joyce finishes him with an axe. Hopper and Murray’s bomb destroys the Upside Down and separates the Abyss from Earth. Eleven remains inside as it collapses, apparently sacrificing herself, but Mike later imagines she escaped and lives somewhere distant. Her survival is never confirmed. Eighteen months later, the others graduate and start new lives, then finish one last Dungeons & Dragons campaign in the Wheelers’ basement as Holly and her friends take over the game.