In the premiere, Veronica Sawyer, a seemingly normal teenager braving the politics of high school, struggles to make sense of her path in life and her connection to her "best friends", the Heathers.
Heather Chandler blackmails JD and Veronica into doing her bidding; Heather Duke and Heather McNamara struggle to adapt to life in the new regime led by Betty Finn.
Veronica, fed up with JD, goes on a double date with Heather Duke and two handsome football players; the school musical auditions commence and Heather Chandler meets unexpected competition.
Heather Chandler tries to double down on her sleeping campaign only to have her brand tarnished; Betty Finn has some suspicions that link Veronica to an unsolved cuddle.
Betty and JD are interrogated by the police as JD is hounded with anonymous text messages tying him to his crimes.
Veronica schools JD on how to be a proper boyfriend; Heather Duke and Heather Chandler spar over control of the student body.
Ousted from power, Heather Chandler decides to swallow her pride and do the impossible: apologize. She spends time with the less-fortunate at Westerburg, and learns from an unexpected source that Heather Duke has a skeleton in his closet.
In response to the spate of violence and unrest in their area, Westerburg decides to stage an "active shooter" training drill in which students are placed on lockdown while the drama teacher goes classroom-to-classroom spraying people with silly string.
As prom looms around the corner, JD and Veronica are moving in opposite directions. She is closer to her friends than she has been all year, while he is trying to use prom to keep Westerburg divided by pitting Heather Duke against Heather Chandler.
Prom brings all of the surviving characters together one last time. JD and Veronica attend separately and fight over some philosophical differences. Heather Chandler tries to make prom about her. Betty Finn returns.