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.
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.
Aria, Hanna, Emily and Spencer desperately want to know why Mike gave their blood samples and why is he visiting Alison in jail... Meanwhile, Hanna is worried about her fee and getting admission in dance... Emily still didn't tell Talia about her biggest fear... Spencer is still confused why Toby is not telling her the truth.
Equipped with their new information about Mona, the Liars decide they need to speak to Alison. But once the truth is out there, Aria quickly learns that Mike's involvement with Mona and this new revelation could have serious repercussions for her family. Determined to keep Mike safe and get Ali out of jail, the Liars intensify their search for information on "A." Meanwhile, Spencer heads to London for an important college interview, and Alison 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 is coming to a close, and the outcome looks even more bleak when the prosecution calls a surprise witness that not only paints Alison in a bad light but also the PLLs and Mike. Desperate to find any evidence or witness to save their friends, Aria, Emily and Spencer race to find someone or something that can prove Ali's innocence and put an end to this nightmare. Meanwhile, Mike becomes a target of "A" when it looks like he might be called to testify, and Ezra and Caleb have differing opinions on what he should do.
"A" has always had fun playing with Aria, Emily, Hanna & Spencer, but now "they" have the biggest game to date in store for the girls. As shocking secrets come to light and the biggest clue to the "A" mystery is revealed, is this one play date the Liars can survive?