The fifth episode of Stranger Things’ third season, Chapter Five: The Flayed, begins with the Mind Flayer’s influence continuing to spread throughout Hawkins, transforming the citizens into a hive mind. Billy is taken to the underground bunker by the Mind Flayer and is used as a vessel to influence more people.
Meanwhile, Dustin and Erica enlist the help of Steve and Robin at the mall to crack the Russian code that they found in the last episode. They are shocked to discover that the code reveals Russians plan to open the gate to the Upside Down underneath Starcourt Mall. While the group is trying to decode the message, they are interrupted by Russians who begin to chase them. They escape, but not before Robin is taken captive.
Joyce and Hopper discover the Russian’s secret base and sneak their way in. They manage to steal Russian uniforms and information from the facility. However, while making their escape they get caught, and Hopper bargains his way to freedom but leaves behind the two Russians they had defeated earlier.
At the same time, Eleven and the group discover that Heather, one of the infected people, has been being used to spy on them. They manage to capture her and use her as a way to lure out more infected people. They then discover that the Mind Flayer has possession of several chemicals stored at the abandoned steelworks that are needed to open the gate.
The group travels to the steelworks and is soon attacked by Billy, Heather, and others who are under the Mind Flayer’s control. Meanwhile, Nancy and Jonathan investigate Mrs. Driscoll’s house, where they find that she is also infected and hypnotized. Mrs. Driscoll attempts to kill them but they manage to subdue her.
As the episode comes to a close, the stakes are raised even higher as the Mind Flayer encompasses Hawkins as the team struggles to stop it. With the clock ticking down, Joyce and Hopper race against time to stop the Russian invasion and the opening of the gate to the Upside Down. The episode ends with one of the most suspenseful cliffhangers yet, setting up an intense finale for the season.