After the shocking events at the school marathon, Aria, Emily and Spencer are sure now more than ever that Mona is up to her old tricks. Hanna, still holding out hope for her former friend, is not so sure. With Mona seemingly popping up everywhere, it sure seems like she has a plan. But with no real evidence to prove Mona is back to her evil ways, how can the Liars prove what they believe to be true? Meanwhile, Aria's fears about her father grow stronger when something vital that is hidden in her room goes missing.

When dealing with matters of the heart, people react in many different ways: Still crushed over her break-up, Spencer continues her downward spiral as she now takes her anger and hurt out on Mona. Caleb, on the other hand, hides his pain by being closed off when discussing his father. But when Hanna devises a plan to bring father and son back together, will that help Caleb heal old wounds or just make things harder? And Aria, who is still missing Ezra, finds she is spending more time with Wes. Meanwhile, Emily and Jason work together to put together the pieces of Ali's trip to Cape May and what really happened during that vacation.

Hanna's new interest in crime novels helps her to come up with a plan to try and figure out whose body is in Ali's grave. While Hanna is on her hunt, Spencer is working overtime to decipher the stories in Ali's diary which she hopes will reveal the identity of Ali's mystery man. But with both girls hot on the trail, will their work lead them straight into "A's" path? Meanwhile, Aria is upset with the new friend Mike has made and Emily's dad is concerned about her behavior.

Alison attempts to regain her position as leader of the gang upon her return to Rosewood High.

Aria hopes Andrew can be her tutor; Spencer helps Jonny with a new project.

Hanna enters a beauty contest and turns to Emily for help; Aria asks Andrew to keep an eye on Mike.

The girls talk to Alison and try to get her out of jail after uncovering Mike's connection to Mona. Meanwhile, Spencer travels to London for a college interview; and Alison turns to someone unexpected for assistance with her murder trial.

Testimony at Alison's trial reveals a plethora of lies; Spencer, Aria, Emily, and Caleb follow a string of clues in hope of uncovering information that will clear Hanna.

The prosecution calls a surprise witness in Alison's trial; the girls hunt for last-minute evidence.

Shocking secrets come to light for Aria, Emily, Hanna and Spencer as the biggest clue to the "A" mystery is revealed.

The girls may have gotten out of the Dollhouse but what happened to them during their time of captivity has lasting effects. With worried loved ones watching over them, the PLLs are home and trying to heal, with not much success. Even with suspected tormentor Andrew in custody, Aria, Emily, Hanna and Spencer fear they are far from safe.

Meanwhile, Alison must deal with her past indiscretions and her notoriety around Rosewood.

The girls’ lives have been turned upside down by their captivity and each one of them is looking for answers to make sense of their ordeal. Aria focuses on Andrew by trying to figure out who this boy really is while Emily tries to connect with a new friend. In true Spencer fashion, she is on a mission to get answers about Charles from Ali and Jason. Hanna wants to bring the four friends back together so they can move past what happened in the Dollhouse.

Meanwhile, Alison is no longer the queen bee/mean girl she once was – but who is she now? A new friend tries to help her find the courage to start anew and find the “new” Alison.