S3E6 · Chapter Six: E Pluribus Unum

Complete story — includes the ending

Eleven, who had just then reconciled with Mike, uses her powers to incapacitate the bio-massed Mind Flayer, forcing it to flee to the mill. In the Russian lab beneath Starcourt, Steve and Robin are captured, drugged, and interrogated, but Dustin and Erica manage to rescue them. With Murray translating, Hopper and Joyce hold Alexei hostage, forcing him to reveal that the Russians are attempting to access the Upside Down and that they are opening a portal beneath Starcourt. Hopper calls Owens to warn the U.S. Government of the threat, but Joyce insists they return to Hawkins immediately, fearing that their kids may be involved. Grigori corners Kline at Hawkins' Independence Day fair, demanding he step up efforts to find Hopper. Mike argues with Max about relying on Eleven's powers and inadvertently admits his ongoing love for Eleven. To find the Mind Flayer, Eleven uses her powers in an attempt to psychically communicate with Billy, learning of his traumatic childhood and finding the Mind Flayer at the mill. Billy senses Eleven's presence, giving the Mind Flayer access to her location, and reveals that the Mind Flayer plans to kill her to avenge her closing the gate. The Flayed converge on the mill, dissolving into an enormous organic mass and merging with the Mind Flayer.