A year after their friend disappears, four girls receive mysterious messages from 'A'.

The circumstances surrounding Alison's disappearance continue to haunt Aria, Emily, Spencer and Hanna as questions arise about the night she went missing.

The discovery of a new piece of evidence about Alison's disappearance brings the FBI to town, and the last thing the girls want to do is go 'glamping' for a birthday party.

Relationships are in flux in Rosewood as the girls face many obstacles. As Noel steps up his pursuit of Ezra, Aria and Ezra begin to feel like there may be no way out.

After a shocking revelation from the police, the spotlight is turned on four little liars who look to be crying wolf. But with everything pointing to Ian, how could the girls be wrong?

Now that Aria, Emily, Hanna and Spencer are in possession of the information that Alison left them, the girls decide that it's time to finally put an end to the mystery surrounding their friend.

Disbelieved by police and families, the tormented quartet is sent for therapy. The chance to share at least some of their secrets proves appealing.

In custody after a testing day, three of the girls count the cost of the tasks ‘A’ set them to save a life.

The Halloween before Alison vanished shows her controlling nature, and reveals other manipulative souls were also active.

An uncomfortable close encounter with their nemesis awaits at least one of the tormented quartet, and a death is promised.

Approaching the second anniversary of Alison's disappearance, a shocking event rocks Rosewood.

As the town becomes a media circus in the run-up to the new trial, the girls are betrayed by someone close to them.

Aria, Emily, Hanna and Spencer crash the Ravenswood Founders Day Celebration after a clue in "A"'s new lair suggests that Ali may indeed be alive.

Who killed Toby's mother? Who hit Alison in the head with the rock the night she went missing? Who is Red Coat? Who killed Bethany? Who is the Black Widow? Why has "A" been targeting the PLLs all this time? After years of torture, Alison, Aria, Emily, Hanna and Spencer finally come face-to-face with their tormentor and learn the story of how and why Charles became "A."

With the stalker threatening to kill all of them if they don’t divulge Charlotte’s killer by the election, the PLLs and company, at wit’s end, must boldly fight back. As Spencer and Toby work together to catch Sara Harvey, Yvonne wonders where Toby’s true affections lie. Ezra finishes the last chapter of his book, finally ready to say goodbye to Nicole; Aria comforts him during this emotional time and old feelings bubble to the surface. While Caleb works intently on his plan to protect Hanna, they reflect on what could have been.

Meanwhile, Alison experiences strange visions and starts to question her sanity; Emily keeps tabs on her to make sure she’s okay.