In a flashback to 1979, Dr. Brenner is experimenting on children possessing supernatural abilities until a mysterious incident kills all of the children except Eleven. In 1986—eight months after the events at Starcourt Mall—Joyce, Will, Jonathan, and Eleven have moved to California, where Eleven struggles with the loss of her powers and is routinely bullied by other students. Joyce receives a porcelain doll in the mail, seemingly from Russia, and finds a hidden note stating that Hopper is alive.
In Hawkins, Mike and Dustin have joined their high school’s “Hellfire Club,” a Dungeons & Dragons club led by the eccentric Eddie Munson. As a result, they miss seeing Lucas win the basketball team’s championship game. Max, who has broken up with Lucas, struggles to grieve Billy’s death. Chrissy Cunningham, a student on the cheerleading team, is haunted by visions of her family and a chiming grandfather clock. While buying drugs from Eddie, Chrissy is possessed and killed by a sentient humanoid creature from her visions.
Source: Wikipedia