Em 1999, um grupo de amigos é abalado pela morte repentina de um deles. Vinte e dois anos depois, a vida de Imogen Adams, de 16 anos, sofre um revés com a morte suspeita de sua mãe — e com uma briga contínua com sua ex-melhor amiga, Karen.
Enquanto Imogen e seus novos amigos planejam se vingar de um inimigo em comum, Karen e sua irmã gêmea Kelly concebem seu próprio plano.
Millwood High enfrenta os efeitos da Semana do Espírito Escolar. Na busca para revelar o misterioso “A”, Imogen descobre alguns segredos. Com as investigações do xerife Beasley, Noa pesa suas opções e Tabby tenta recuperar provas vitais.
After their punishment comes to an end, the girls cement their friendship when Imogen needs them most.
Desperate to keep her mothers house, Imogen throws a Halloween party to raise cash.
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 isnt himself. Meanwhile, Imogen considers her babys future, and Faran confronts everything thats been plaguing her.
The friends work together to uncover Imogen and Tabbys assailant during the Annual Thanksgiving Millwood High Blood Drive. Later, Sidney confronts Tabby about her secrets.
Despite coming clean about “A,” the friends find their troubles are far from over – especially as the results of the groups 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 its too late.