On the night of a major school gala, the "Perfectionists"—Caitlin, Dylan, and Ava—along with Alison and Mona, are convinced that is the killer. Their plan to expose him is complicated by Dana Booker, who continues to leverage secrets against them to maintain her investigation. Key Plot Developments

The group attempts to use a recording of Dana confessing to manufacturing evidence to get her fired. However, Claire Hotchkiss is impressed by Dana's ruthlessness and keeps her on.

It is revealed that Taylor actually created Beacon Guard , the town's pervasive surveillance system, following her father's murder.