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.

As they try to pay tribute to Alison's memory, the four friends are faced with unresolved issues. With 'A' taunting them every step of the way, can the girls forge ahead and leave the past behind?

Tired of being harassed by 'A', the girls decide to put a stop to the anonymous emails and text messages by blocking all unknown users. But the friends' problems are far from over.

Trying to ignore 'A' backfired for the girls, and now they must pay the penalty. They must also deal with typical teenage drama - the boy kind.

The homecoming decorating committee is knee-deep in balloons, and girls are jockeying for position to be the queen, while four friends from Rosewood just try to stay afloat.

In the aftermath of the disastrous homecoming dance, the girls try to sort out the devastation that is left behind. If the little liars don't act fast, the situation could go from bad to worse.

After much planning, the day of Alison's memorial is around the corner, and the girls are ready to say their goodbyes. But their last-minute preparations soon get derailed.

A day of SAT testing is put on hold when a violent storm hits Rosewood, but the girls are stuck inside the school dealing with the drama that follows them everywhere.

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.

Moments after Hanna is hit by a car, the girls' world is turned upside down. 'A' is no longer content to play a game of cat and mouse, and things take a far more precarious turn.

Hanna's return home from the hospital should be a joyous event, but being stuck in a wheelchair and feeling haunted by 'A' makes it feel more like a Hitchcock nightmare than a proper homecoming.

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.

As the school gets ready for the dance-a-thon, Aria, Emily, Hanna and Spencer have more on their minds than just raising money for the school trip to Washington DC.

The girls try to resume a sense of normality in their lives, but even the simple tasks of dating and extracurricular activities meet with strife.

A crucial swim meet for the Rosewood Sharks is the setting where Aria, Emily, Hanna and Spencer experience a lot of turmoil. Emily and Paige go for round two as they are pitted against each other.

What happens to one little liar when parent-teacher conferences come around and her father sits face-to-face with the love of her life?

As their doubts, fears and suspicions grow, Aria, Emily, Hanna and Spencer start to wonder what the true face of evil looks like. Is it the girl who will do anything to keep her loved ones near?

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?

Everyone has a secret in Rosewood and it's only a matter of time before it is revealed. Four girls know this to be especially true and are reminded of it on a daily basis.

Rosewood's Founders Festival sets the stage for more secrets. Everyone has something to hide - whether it is a secret romance, or revealing a true identity and true intentions.

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.