Plot

Terror reigns in the food court when the Mind Flayer comes to collect. But down below, in the dark, the future of the world is at stake.

Hopper, Joyce and Murray head to the Russian base to activate the keys that are opening The Gate, with the support of Steve, Robin, Dustin and Erica by radio. El and her friends are leaving the Starcourt Mall when they realize that Billy has stolen the ignition cable from Nancy's car and they are forced to seek shelter from the Mind Flayer in the mall.—Claudio Carvalho, Rio de Janeiro, Brazil

Eleven's wound from the Mind Flayer's bite has something moving under the skin. Jonathan finds a knife and a wooden spoon in a mall restaurant. He sterilizes the knife and has Eleven bite down on the spoon handle while he cuts open her wound. Eleven, in pain, uses her powers to remove the piece of tentacle still inside her.

Hopper, Joyce, and Murray show up at the mall and they and the kids devise a plan to stop the Russians and close the gate. Hopper, Joyce, and Murray will go underground to find the keys to close the gate. Dustin and Erica will help them navigate over walkie talkie from Dustin's radio on the hill in Hawkins. The group splits up. Dustin, Erica, Steve, and Robin (code name "Scoops Troop") go to Dustin's radio to walk the adults through the underground maze, the adults go underground and Nancy and Jonathan are instructed to take Eleven, Mike, Will, and Lucas (code name: "Griswold Family") to Murray's house.

Hopper, Joyce, and Murray make it back to the Russian base, but are discovered by Russian officials. Hopper shoots all the officials and the three steal their uniforms. Disguised, and with Murray to speak Russian, they are able to get past the guards. Murray crawls through the air vents (continuity error: now more than large enough for a grown man, despite the group needing a child to navigate them before) as Dustin gives him directions. While waiting for Murray, Joyce and Hopper make plans to have a date later that week. Murray makes it to the powerhouse of the machine that powers the gate and is able to begin shutting it down. Hopper and Joyce get to the safe containing the keys and need to enter Planck's Constant as the code, but Murray has given them the incorrect number.

Nancy tries to drive away with the others in her car, but her car will not start. Jonathan discovers that the ignition cable is missing, and Billy shows up. The group retreats back into the mall where they try to radio Dustin. They take the ignition cable from the display car in the mall (the one Eleven threw at the Russians). Eleven's powers are weakened considerably after her encounter with the Mind Flayer. The Mind Flayer crashes through the ceiling of the mall. Max, Eleven, and Mike try to escape through the back door of the GAP, but Eleven trips and the Mind Flayer follows.

From the hill, Steve sees the mall under attack from the hill and Dustin tries to radio the Griswold Family, but they don't have the walkie talkie. Robin and Steve leave to rescue them. The kids escape the mall, but Billy tries to attack them with his car. Steve and Robin arrive just in time to stop Billy from slamming into Nancy's car and they escape with Nancy, Jonathan, Will, and Lucas.

Dustin radios Suzie to get the correct Planck's Constant number. Suzie, not knowing the gravity of the situation, says that he needs to do something for her first. Reluctantly, Dustin sings the theme song from "The NeverEnding Story," (heard on the walkie talkies by everyone else) and Suzie gives him the code, which Hopper enters on the safe. They make it to the room by the machine powering the gate, but just as they are about to turn the two keys which will close the gate, Grigori attacks Hopper. The two men fight, ending up on the platform next to the machine.

Billy sees Eleven, Mike, and Max outside the mall and corners them. Eleven's powers are drained and she can't defend them. Billy knocks out Mike and Max and carries Eleven back to the mall where the Mind Flayer approaches. Just then, the others, who followed the Mind Flayer back to the mall, attack it with fireworks. This keeps it occupied for a while, but they run low and Steve radios Dustin to say they are almost out of time. Dustin radios Hopper and Joyce to close the gate immediately. Joyce hears the message and tries to reach both keys to turn them at the same time. Hopper throws Grigori into the whirling gears of the machine. More Russians approach and Joyce and Hopper realize that Hopper will not have enough time to get back to safety, and that he will likely be killed in the ensuing explosion. Hopper nods to Joyce and she flips the switches. The machine explodes, killing the Russians on the platform (Joyce, who is behind a glass screen is unharmed), and the gate closes, leaving Joyce tearfully staring at the platform where Hopper was a moment ago.

Billy drags Eleven to the Mind Flayer and holds her down. She tells him about his own memories of being on the beach with his mother - probably the last time that Billy was happy. This touches the part of Billy that is still himself and he cries. The kids run out of fireworks, and the Mind Flayer turns on Eleven again. Billy stands in its way and the Mind Flayer kills him. At that moment, Joyce closes the gate, and the Mind Flayer collapses. In the aftermath, Dr. Owens and soldiers from Hawkins Lab infiltrate the Russian's lair. The mall catches fire from the fireworks, and Joyce finds the kids outside the mall. She tearfully embraces Will, and then sees Eleven, conveying with her eyes what happened to Hopper.

It is three months later, and Hopper as well as all the people possessed by the Mind Flayer are presumed to have died in the mall fire. Mayor Kline has been arrested for collusion. Steve and Robin get jobs at the local video store. The group helps Joyce and her family pack up her house because they are moving to California. Now that Hopper is gone, Joyce has adopted Eleven. Eleven's powers no longer work, although Mike assures her that they will come back. They make plans to see each other in the future, and Eleven tells Mike that she loves him. As Joyce is going through boxes, she finds the heart to heart speech that Hopper wrote for Mike and Eleven, but never gave. She gives it to Eleven, who reads it, hearing Hopper's voice tell her that she brought happiness and meaning back into his life. Eleven leaves with the Byers family.

In Kamchatka, Russia, soldiers are guarding a prison. One says to the other, "Not the American," and they remove a Russian prisoner from his cell. They throw him into a large cage, and open a door, out of which the Demogorgon crawls and attacks the prisoner.