20 years after a series of tragic events that almost tore the town of Millwood apart, both the young and old generations of Millwood must face the consequenses of their past when an unknown assailant seems to know an awful lot about their secretive history.

Imogen and her new friends plot revenge on their common nemesis, while Karen and her twin sister Kelly hatch plans of their own.

As Millwood deals with the aftermath of recent events, Imogen uncovers secrets to unmask "A." Beasley gets closer to the truth, Noa weighs her options, and Tabby tries to retrieve some evidence.

After their punishment comes to an end, the girls cement their friendship when Imogen needs them most. Meanwhile, Noa find herself in A's cross hairs.

Desperate to keep her mother's house, Imogen throws a Halloween party to raise cash. Unfortunately, the presence of an unwanted house guest casts a shadow over the celebrations.

As Imogen and Tabby dig into the mystery surrounding Angela Waters, Faran deals with the scars of her past.

As the Millwood carnival approaches, Mouse and Tabby each struggle with secrets, and Noa notices Shawn isn't himself. Meanwhile, Imogen considers her baby's future, and Faran confronts everything that's been plaguing her.

The friends attempt to get to the bottom of one mystery, while Imogen pursues answers to another. Then, a much needed girls' night prompts Sidney to confront her daughter about a long-held secret

Despite coming clean about 'A,' the friends find their troubles far from over, especially as the results of the group's clandestine blood drive push Tabby towards a new suspect.

As "A" doubles down, the friends must work quickly to uncover the link between Angela Waters' death, their mothers, and their mysterious foe - before it's too late.