Plot

Strange surprises lurk inside an old farmhouse and deep beneath the Starcourt Mall. Meanwhile, the Mind Flayer is gathering strength.

The elevator where Steve, Robin, Dustin and Erica are trapped goes uninterruptedly down until it stops. When Russian agents arrive, they succeed to leave the shaft but they cannot leave the underground base. Hopper and Joyce seek a machine at the real states recently bought by Kline until they find the location. However the Russian agent arrives but they succeed to flee with a Russian scientist. However their car breaks and they are forced to hijack another car to visit a Hopper's friend that speaks Russian. The group of teenagers head to the hospital to visit Mrs. Driscoll and they have a dreadful surprise.—Claudio Carvalho, Rio de Janeiro, Brazil

Hopper and Joyce explore one of the purchased properties and discover two Russians talking. Grigori, the thug who attacked Hopper, appears with an automatic rifle. After a fight, Hopper and Joyce escape with Alexei, one of the Russian scientists and drive away as several of Grigori's bullets hit Hopper's truck. He attempts to repair the car, but it explodes, leaving the three of them to walk until they find a convenience store where they commandeer a car.

Dustin, Steve, Robin, and Erica find themselves miles underground. They climb out the top of the elevator and witness men coming to collect the boxes. They stop the door as the men exit and manage to get out of the elevator, only to find themselves in a long corridor, meant for transporting the green vials. They are nearly captured by a Russian, but Steve knocks him out and they discover that the Russians have made a giant weapon that has opened a gate into the Upside Down.

Nancy and Jonathan meet up with Eleven, Max, Mike, Lucas, and Will to discuss what they have witnessed. Based on Nancy's description of Mrs. Wheeler's reaction during Billy's sauna test, they determine that she is infected by the Mind Flayer and that others probably are too. They go to Heather's house where they see evidence of the parents being attacked. (Nancy remembers that Tom had a band-aid on his forehead.) There are cleaning chemicals out, indicating that the parents have been ingesting them. Nancy remembers that Mrs. Driscoll was saying that she had to go back. They determine that all the victims are brought to a specific place which they can find through Mrs. Driscoll.

Hopper and Joyce bring Alexei to Murray, who speaks Russian and can translate.

Nancy and Jonathan bring the kids to the hospital and the two of them go to see Mrs. Driscoll but find her room empty. Tom appears with bloodstains on his clothes and tells them that she has gone home and that he was hoping they would return. Jonathan knocks him out and they escape only to find Bruce, one of the jerks from the Hawkins Post, also covered in blood. He chases them through the hospital (in a zombie-like state) and they pass the dead bodies of hospital staff. Bruce traps them in a room where he hits Jonathan with a metal stool until Nancy stabs him with scissors. Bruce chases Nancy and Tom attacks Jonathan. Nancy hits Bruce in the face with a fire extinguisher and Tom gets the same facial injuries. Jonathan stabs Tom in the throat with the scissors. Both men's bodies melt into a red goo that oozes across the floor and meets to create a horrifying monster.