In the fifth episode of the first season of Stranger Things, Hopper sneaks into the lab and reaches the lower level using force, where he finds a peculiar passage that the staff manages to sedate him with a syringe. Lonnie, Joyce’s ex-husband, tries to convince her that her visions related to Will are just a hallucination, as his body has already been found. The boys believe that Will is trapped in another dimension, which El calls “the Upside Down,” where a monster – which she named Demogorgon after a creature from Dungeons and Dragons – resides. After the funeral, friends ask Mr. Clarke about parallel dimensions, and he tells them of the hypothetical possibility of existence of portals between spaces.

Hopper wakes up at home and finds a bug, indicating that his house has been visited. Hopper’s assistants tell him that Barb’s car has been found outside the town. The boys try to find a magnetic anomaly associated with the portal using a compass. El remembers how she was placed in a sensory deprivation tank to enhance her telekinetic abilities, and during this experiment, she discovered a strange object. El warns friends about the dangers of the portal and deflects the compass needles to stop them from finding it. Lucas accuses El of betrayal, but Mike defends her, which leads to a fight between him and Lucas. Meanwhile, in the woods, Nancy and Jonathan discover a portal to the Upside Down, where she sees a monster feasting on a wounded deer.