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.
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.
A search for Mona's laptop is underway, and it may lead to Spencer and Caleb to break Toby's rules. Meanwhile, Aria gets sidetracked when she's about to come clean to Ezra; and Hanna and tries to keep her mom's secret when Pastor Ted returns.
The liars desperately want to know why Mike gave their blood samples and why he's visiting Alison in jail; Hanna is worried about her fee and getting admission in dance; Emily still hasn't told Talia about her biggest fear; Spencer is still confused with why Toby's not telling her the truth.
Equipped with their new information about Mona, the liars decide they need to speak to Alison; Aria quickly learns that Mike's involvement could have serious repercussions for her family; The liars intensify their search for information on "A"; Ali looks to someone surprising for help with her murder trial.
The PLL's struggle to find evidence against "A" to help an imprisoned Hanna get out of jail. Meanwhile, Alison's trial is expected very soon and not only does it decide her fate, but it also unravels a lot of secrets the group has told.
Alison's trial comes to a close when the prosecution calls a surprise witness; The liars race to find someone or something that can prove Ali's innocence; Mike becomes a target of "A" when it looks like he might be called to testify.