In 1999, a group of friends is shocked by the sudden death of one of their own. 22 years later, their daughters are brought together after a series of cryptic messages from a mysterious enemy.
Imogen and her new friends plan revenge on their common enemy, while Karen and her twin sister Kelly devise their own plans.
Imogen, Tabby, Noah, Faran and Mouse investigate recent events and Angela Waters' past, uncovering secrets about their mother's connection to her death. Sheriff Beasley closes in on the girls, and they discover that A is watching them.
After completing their punishment, the girls strengthen their friendship when Imogen needs them most, while Noa finds herself targeted by A.
In order to keep her mother's house, Imogen throws a Halloween party to raise money, but the presence of an unwelcome guest in the house casts a shadow over the festivities.
As Imogen and Tabby uncover the mystery surrounding Angela Waters, Faran confronts the scars of her past.
As the Millwood carnival is nearby, Mouse and Tabby grapple with secrets, Noa feels that Shawn is acting differently. Imogen ponders her child's future, while Faran faces everything that has been troubling her.
The girls try to get to uncover the truth about one mystery, while Imogen strives for the answers to another, and Sydney confronts her daughter about a long-kept secret.
Despite telling the truth about A, the girls find that their problems are far from over, especially as the results of the group's secret blood drive lead Tabby towards a new suspect.
As A redoubles his efforts for revenge, the girls must work fast to uncover the connection between the death of Angela Waters, their mothers, and their unknown enemy before time runs out.