Nikki joins the party — and the newly formed Hawkins Investigators Club. Strange things take root at a nearby farm and shake up the Winter Festival.

The kids look for answers about the mutant creatures plaguing their town and get a helpful lesson from Mrs. Baxter, their substitute science teacher.

A worried Mike decides to come clean to Hopper, and Dustin drags Steve into the H.I.C. Nikki welcomes Will to the mosh pit. Lucas and Max hit the arcade.

When a photo that could put El in danger gets sold to a popular tabloid, the kids pull Nancy into a heist to get it back. If they can't? It's game over.

As a blizzard bears down on Hawkins, Dustin goes on a side quest, and Max and Lucas hear a cry for help. A bold move lands some of the gang in detention.

Lucas and Max seek higher ground to call in a Code Red. Across town, Will, Mike and Nikki are snowed in at school — and El can see they're not alone.

Dustin finds danger at the Food Mart when two terrifying creatures break in. The gang gears up to go underground just in time for Nikki's birthday.

In the wake of a shocking revelation, the H.I.C. digs in to investigate, splitting up into teams to search for more clues and uncover the truth.

With time running out, the party pulls together for a brave battle to stay alive. Friends have to help friends — because Hawkins' future depends on it.