The action takes place in 1983 in Hawkins, Indiana. In the laboratory of the US Department of Energy, an unknown creature attacks a scientist, and this makes all agencies interested in what’s happening. At the same time, twelve-year-old Will Byers disappears after encountering an unidentified creature on his way home after playing Dungeons & Dragons with his friends. Every day, Will’s anxious mother, Joyce, tries to contact her son by phone, but no one answers.

One day at a local diner, Benny (Chris Sullivan), the owner of the establishment, spots a bald-headed girl in a hospital shirt who is trying to steal food. He feels sympathy for the child and decides to feed her, but later a woman posing as a social worker comes for the girl. After Benny learns that the woman has no identification, he tries to help the child and calls the police, but later he is killed by the woman. Benny’s death forces National Security agents to begin searching for the girl, but she finds salvation and escapes.

Meanwhile, Will’s best friends, Lucas, Mike, and Dustin, begin to search for him in the woods and meet the girl. The girl is scared of them at first, but then realizes that they can help her, and tells them that she has psychic abilities and can help them find Will. Together they try to uncover the mystery and find answers to all the questions that arise in their heads.