As Hopper and Joyce move through the dark and hostile environment of the Upside Down, he tells her to slow down and take deep breaths. Hopper recalls chasing his young daughter Sarah and noticing her labored breathing, which was the first sign of her illness.

Mike tries to convince the other two to help the others fight the Demogorgon, but Lucas and Dustin say their role is to keep El safe and away from the bad guys. Dustin goes to the canteen to find some food the lunch lady is stocking up on.

Nancy and Jonathan inform each other of their plan to lead the Demogorgon into a trap. They cut each other's palms for bait. They then lick each other's wounds and wait for the enemy to arrive. Suddenly, Steve came and knocked on the door to apologize. Nancy asks him to leave but he persists. He notices Nancy's gang and finds that the house is a mess and that they carry guns. Nancy points a gun at Steve to get him to leave. Suddenly the lights flashed and they armed themselves. The ceiling began to open and the Demogorgon fell. Steve yelled for an explanation, but both of them just had to wait and get their guns ready. Nothing happened, so they checked the empty hallway. Hopper and Joyce find an empty egg and the remains of Castle Byers. Hopper finds Will's stuffed lion cub, which resembles Sarah's, during chemotherapy.

Demogorgon
Jonathan, Steve and Nancy return to the living room with their weapons. Steve returned to the car only to see the lights blinking again. It quickly shuts down completely and the Demogorgon lunges at Jonathan. Nancy shoots him until the clip ends, but he continues. Steve comes to the bat and fights it, leading it to the bear trap. Jonathan deals the final blow and burns him. When the flame goes out, the remains of the creature disappear, leaving only spots on the ground.

Hopper and Joyce enter the Upside Down version of their home, which will activate the lights in the real world. Joyce and Jonathan heard each other through their echoes.

Mike invites Eleven to live with them after it's all over. She asked if she looked like her brother at the time, but Mike refused. She asks him not to lie, so he invites her to Snow Ball. It would be weird if they were siblings. He explained by kissing her.

Suddenly, the villains come to Hawkins Middle and see the swimming pool in the gym. The children were trapped in a corridor, but El killed them all by bleeding their brains. She fainted shortly after.

Brenner asks the boys to leave El while the other guards subdue them. He wakes her up and promises to make things better. She called Mike and the lights flashed. To be continued.