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.

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.

A new clue could lead the girls down the wrong path. Emily remembers something new from the other night but the recollection suggests a very surprising suspect.

Paige's past comes back to haunt Emily. Aria gets a surprise from Ezra's past.

Distracted Spencer’s anger is let-loose on Ezra, hurting Aria. Emily and Hanna each end up at the police station.

Some secrets of Mona’s asylum stay come to light, a corpse must be faced, and a lost child tracked down.

Spencer and Emily make plans to visit a nearby college, but they have very different agendas for their time spent on campus.

Still living at a motel, Emily is taken aback when Ali's mother offers to let her move into Ali's old room and is shocked when the other Liars insist Emily take up the offer.

Hanna's interest in crime novels helps her to come up with a plan to figure out whose body is in Ali's grave. Spencer is working overtime to decipher the stories in Ali's diary.

Spencer is determined to finally tell Aria what she has found out about Ezra, but Emily and Hanna are worried about what it could do to their friend.

Spencer is reeling about the memories from her 'lost summer', Aria is nursing a broken heart, Emily struggles with Paige's betrayal and Hanna attempts to get back into dating.

Mona returns to Rosewood in a very fragile state as she must answer to the police for faking her death. Matters only get worse when she is confronted by Lesli’s sister about Lesli’s inadvertent involvement in Mona’s plot. Hanna is determined to help Mona out, not only to reassure her she is safe from Alison but also to try and repair Mona’s friendship with Lesli. Emily tries to help Sara with her troubled home life by encouraging her to explore the possibility of emancipation. Spencer, on the other hand, finds help from someone from her past.

Meanwhile, Alison grows closer to Lorenzo as she looks for support outside of her family.

With all signs pointing to Lesli as the tormentor in the hoodie, the PLLs are on a mission to get concrete proof before bringing their findings to the police. But as the girls ramp up their investigation, "A’s" threats escalate.

Meanwhile, a friend of Emily’s makes her a surprising offer, and Spencer is pressured by her family to make an important decision.

Aria, Emily, Hanna and Spencer find themselves back in familiar territory with the Rosewood P.D. knocking at their doors looking for answers and their actions now affecting the loved ones around them. With her mother's job on the line, Hanna tries to come up with an alibi that could save all four of them with the help of her old high school friend, Lucas.

Meanwhile, Emily comes clean about the last five years, and Aria goes the extra mile to keep Ezra's second book in play with her boss.

After the stalker nearly killed Emily, the Liars begin to take the threats more seriously and attempt to keep their mouths shut to prevent any further harm. Caleb must deal with the collateral damage of taking the blame for the leak about Yvonne; Spencer tries to comfort him and get him to tell the truth. Emily goes on a mission to track down who came after her. Aria and Ezra move forward with the novel.

Meanwhile, Hanna avoids dealing with her personal life.