Plot

The government comes searching for Eleven. Eleven looks for Will and Barb in the Upside Down.

Lucas warns his friends that the bad men from the Hawkins Laboratory are coming and they must flee. They are pursued by Brenner and his agents and El uses her power to flip a van and stop the others. They hide in a junkyard and meet Lucas. At the police station, Jonathan is released by Hopper and Joyce and he and Nancy tells about the monster. Troy arrives at the station with his mother and tells about El's abilities. Hopper, Joyce, Nancy and Jonathan seek out Mike, Dustin and Lucas and they use Will's walkie-talkie to contact them. They meet the boys and El at the junkyard and head to Nancy's house, where Dustin calls Mr. Clarke to learn how to make the deprivation tank.—Claudio Carvalho, Rio de Janeiro, Brazil

Mike cleans up Eleven back at his house and tells her she is pretty. Lucas contacts the others on his walkie talkie and tells him that the men from Hawkins Lab are coming for Eleven. The kids flee on their bikes but are followed by the repair vans we now know are disguised vehicles for Hawkins Lab. One van comes straight for the kids, but Eleven causes it to flip over in the air and crash. The kids escape to a junkyard where they hide in an abandoned bus.

Hopper and Joyce go to the police station to get Jonathan. Jonathan and Nancy explain about the monster and Joyce reprimands Jonathan for going after it alone. At the station, Hopper encounters Troy and his mother attempting to report the girl who broke Troy's arm. Once Troy describes the girl's appearance and abilities, Hopper knows that it's Eleven. He learns that she is with the boys and they realize that they need to find the children before Brenner does. Jonathan locates Will's walkie talkie and they try to contact Mike. The boys hesitate for a while before answering, thinking it might be a trap, but ultimately tell Hopper their location.

Dr. Brenner meets with Mr. and Mrs. Wheeler and tells them that Mike has been hiding a dangerous girl and that Mike is now in danger. He asks for their trust on the matter and tells them to stay at home while he tries to find the kids. They are shaken, but agree.

The men from the lab arrive at the junkyard and nearly discover the children, but Hopper gets to them first. Back at Joyce's house, they explain to the adults about the Upside Down. Eleven tries to make contact with Will and Barb on the walkie talkie, but is weakened from flipping the van and isn't able to connect. She tells them that she can still make contact with a "bath" or sensory deprivation tank. Dustin calls Mr. Clarke (interrupting his date night) to ask how to build a sensory deprivation tank. They set up a kiddie pool in the Hawkins Middle School auditorium and steal hundreds of pounds of deicing salt to add to the water. Mike and Nancy have a nice moment where they agree not to keep secrets from each other anymore. Mike asks Nancy if she likes Jonathan and she denies it. Nancy asks Mike if he likes Eleven and he denies it.

Joyce thanks Eleven for her bravery and for helping her family. She reassures Eleven that she will be with her the entire time and to let her know if it gets too scary. This is the first time Eleven has been shown this kind of sympathy from an adult and it goes in direct contrast to her treatment by Dr. Brenner, who although somewhat affectionate, does not care about Eleven's mental well being and does not respond to her when she is afraid.

Eleven floats in the sensory deprivation tank and finds herself in the void. She discovers Barb's gruesome dead body and screams "Gone!" over and over until Joyce's voice calms her. She finds the Upside Down version of Castle Byers covered in slimy web and vines with Will inside, cold and weak, but alive. She tells him that Joyce is coming for him and he says to hurry. It is clear that he does not have much time left to live.

Hopper and Joyce leave for Hawkins Lab, leaving Nancy and Jonathan to watch the kids. Nancy realizes that Hopper and Joyce could run into the demogorgon in the Upside Down and that they need to distract it from them. They leave the kids at the school and go back to the police station where they steal back their weapons and bear trap. Hopper and Joyce break into the lab, but are captured by officials. The episode ends with a freezing Will softly singing "Should I Stay Or Should I Go" and hearing the demogorgon outside Castle Byers. The walls of the fort suddenly break in.