Twenty years after a series of tragic events almost tore Millwood apart, an unknown assailant seems to know all about the town's secret history.
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 Millwood deals with the aftermath of recent events, Imogen uncovers secrets that may unmask 'A'. Beasley gets closer to the truth, 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.
As the Millwood carnival approaches, Mouse and Tabby both struggle with secrets, and Noa notices Shawn isn't himself. Meanwhile, Imogen considers her baby's future.
The friends attempt to get to the bottom of one mystery while Imogen pursues answers to another. A 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 liars must work quickly to uncover the link between Angela Waters's death, their mothers and their mysterious foe before it's too late.
Imogen and her new friends plot revenge on their common nemesis, while Karen and her twin sister Kelly hatch a plan of their own.