It's been a year since the disappearance of her best friend Alison, and Aria Montgomery has returned from her father's sabbatical in Iceland to a whole new dynamic in Rosewood. Her former friends, Hanna, Spencer, and Emily have all disbanded – and the formerly chubby, gawky Hanna, has become the new Queen Bee. Aria's fling with a cute, young college grad named Ezra goes awry when he shows up at her first day of class as Mr. Fitz, her new English teacher. Hanna shoplifts a pair of expensive sunglasses from the local mall and gets caught – though the man on the case, Detective Wilden, has his sights more set on her newly single mother, Ashley. Meanwhile, Emily is secretly wrestling with her sexuality, sparked by the addition of a spunky new girl on the block nam ed Maya, and all-star student Spencer must deal with her sister's flirtatious new fiancé.
Each girl harbors a secret too personal and scandalous to ever reveal, though a sudden string of ominous messages from "A" threatens to expose them all. Is there friend Alison still alive and watching - or is it someone else completely, toying with our pretty little liars?