The episode begins with the Hawkins group facing a formidable new threat from the Upside Down. The newest addition to their ranks, Nikki, joins in the fight against this monstrous entity. Using her powers, El immobilizes the creature against a wall, revealing that Charlie, one of the bullies from the previous episode, is trapped inside it, seemingly sustaining its life force. Once freed, El tears the creature in half, and Charlie appears to be unharmed. This revelation introduces us to Nikki properly, who promises not to reveal the existence of the otherworldly threat.
The group comes up with the idea of forming the Hawkins Investigative Club (HIC) to uncover the mystery behind these strange occurrences. Nikki joins the crew temporarily, and we learn that Mrs. Baxter is her mother. As they get acquainted, strange Demo-roots strike again at the farm, leading to a tip at the HIC. They put up flyers all over town to investigate.
Dustin reluctantly heads off to check out a tip about the Sloth Man, while Max suggests that Mike take El to the Winter Festival that night to lift her spirits. They're not alone at the festival, as Nikki and Will are also present. Nikki encourages Will and effortlessly wins carnival games. Meanwhile, Dustin stumbles upon Charlie in the woods, who appears erratic and jittery.
Max and Lucas go to the farm where they find a couple of kids holed up inside and the pumpkin patch in disarray. When they enter the pumpkin patch, all the pumpkins suddenly come to life, sprouting roots and chasing them into the barn. They ride a tractor out and crush most of these "Pumpkin foes," but there's a catch. The best pumpkins are en route to the Winter Festival's pie-eating contest. When Dustin and the others race in to stop the contest, one of the girls, Rosario, gets infected.
