With the events of New York behind them and back in Rosewood, the Liars are unsettled to still be living under a cloud of secrets. Aria is haunted by the recent past events, while Emily, Hanna and Spencer try to wrap their head around the new normal. Alison, on the other hand, is still sleeping with one eye open as she is forced to stay at home with her family - who she doesn't trust. Meanwhile, Jason's odd behavior and Kenneth DiLaurentis' search for Jessica starts to raise eyebrows about her disappearance.
Now being forced to live through Ali's latest lie, Aria, Emily, Hanna and Spencer try to cover their tracks, while simultaneously trying to piece together what happened in New York. Hanna and Aria have to close loose ends with the two people who know the truth about Ali's story, Mona and Ezra. Spencer and Emily try to find out the truth about Jason (recurring guest star DREW VAN ACKER) and his whereabouts the night they were in New York. Meanwhile, now that Ali is back, Hanna starts to examine who she really is: Hefty Hanna or Queen Bee Hanna.
The girls are keeping their distances from Alison and still trying to figure out why. Spencer finds out her father has a little more than something to do with Jessica DiLaurentis's murder. Meanwhile, Hanna finds out something too. During a routine checkup Hanna finds a scar she has never seen before. Aria is obsessed with Shana and wants to know more about her.
The day has finally arrived: It's Alison's first day back at Rosewood High and neither the Liars nor Alison are really ready for it. Determined to put on a brave face, Alison also hopes to help heal the damage she did years ago. But are apologies enough for those who Alison has hurt in the past? Not if Mona and her army have anything to say about it. Meanwhile, 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 and quickly gets down to business finding any answers she can about a patient of interest to the Liars. But she quickly hits a snag when she comes across an aggressive patient that may be the key to what the Liars are looking for. Also searching for answers, Spencer takes a note from Ezra's play book by borrowing some of his spy equipment to keep a closer eye on the home front. Meanwhile, Hanna is caught at odds when Ali and Caleb butt heads, and Emily seeks help from her friends when her mom invites Ali over for dinner.
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, seking 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.