Original Sin (s01): Pretty Little Liars:

"A" is eventually unmasked as Archie Waters , the twin brother of Angela. He was working under the direction of Marshall Clanton, the school principal and Angela’s secret father, who sought revenge on the girls' mothers for their past cruelty toward Angela. Meet the New Liars

A tech-savvy girl who uncovers secrets about her own past, including a near-kidnapping as a child. Pretty Little Liars: Original Sin (S01)

A disciplined ballerina who begins to suspect "A" is linked to the mysteries surrounding her classmates and parents. "A" is eventually unmasked as Archie Waters ,

In 1999, a group of friends was rocked by the tragic death of a girl named Angela Waters during a New Year's Eve party. Decades later, their daughters—Imogen, Tabby, Noa, Faran, and Mouse—are brought together when "A" begins harassing them. Pretty Little Liars: Original Sin (S01)