In 1999, a group of friends is rocked by the sudden passing of one of their own. Twenty-two years later, their daughters are pushed together by a mysterious foe.

As Imogen and her newfound friends plot revenge against a mutual nemesis, Karen and her twin sister Kelly hatch an insidious plan of their own.

In the wake of Spirit Week, Imogen unearths long-buried truths on her path to unmask the mysterious "A". After Sheriff Beasley closes in, Noa, Faran, and Mouse weigh their options, while Tabby works to recover vital evidence.

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

Desperate to keep her mother's house, Imogen throws a Halloween party to raise cash - but the presence of an unwanted 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. After Shawn confronts Marjorie, Noa questions her relationship with her mother, while Mouse spots a familiar face on her first date.

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 are 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' passing, their mothers, and their mysterious foe... before it's too late.