The liars are forced to live through Ali's latest lie; Hanna and Aria have loose ends with two people who know about Ali's story; Spencer and Emily try to uncover Jason's whereabouts in New York.

The liars keep their distance from Ali; Spencer finds out Peter has a little more than something to do with Jessica's murder; Aria wants to know more about Shana.

Ali returns to Rosewood High and hopes to help heal the damage she did years ago, but not if Mona and her army have anything to say about it; Caleb and an old foe return to Rosewood.

With 'A' back in their lives, the girls are determined more than ever to know his/her identity. While Ali prepares to run away from Rosewood, Hanna faces a challenge in her relationships. Detective Tanner digs deeper into the death of Shana.

Aria begins her volunteer work at Radley; Spencer borrows Ezra's spy equipment to keep a closer eye on the home front; Ali and Caleb butt heads.

As Hanna's downward spiral continues, an unfortunate incident with Zack threatens to strain her friendship with Aria. Spencer and Emily dig deeper into Bethany's relationship with Mrs. Dilaurentis.

Spencer confronts Caleb regarding Hanna's issues; Aria opens up to Ella and questions her marriage to Zack; Emily and Spencer close in on Noel's motives and a call from detective Tanner has Alison perplexed.

All eyes are on Alison as she struggles with her response to Cyrus' confession. Melissa hints at knowing the truth and warns Spencer to keep away from Ali. Aria mulls over Spencer's plan of letting everything out in the open with Tanner.

Emily is on the hunt to find out the truth about Alison, seeking unlikely help from Ezra Fitz for information about Cyrus and Alison's connection. Meanwhile Melissa's secret is finally revealed, Hanna asks for Spencer's and Toby's help with Caleb and his drinking problem.

The girls join forces with Mona to figure out why Ali reached out to the police. Alison's actions put Spencer in the cross-hairs of Bethany's murder investigation. Mona reveals the truth about Ali, resulting in an aching loss.