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

One of Aria's past indiscretions is fodder for a new "A." and Emily recalls a crucial event from the night she lost her memory.

Spencer asks questions, but stumbles upon a larger secret, while Aria agrees to be Jenna's accompanist.

Visiting Mona is driving a wedge between Hanna and Caleb and Hanna is forced to weigh up how honest to be with him.

Jenna throws a party to die for and the Liars are suspicious when Garrett is let out of prison to visit his mother.

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.

Hanna is worried that Detective Bryce is trying to frame her and the others turn to a very unlikely person for help.

Spencer asks Caleb for help. Aria learns about Ezra's past. Emily is worried about how Paige will be affected by everything "A" has done to her.

After Spencer turns in desperation to Cece for help with her college application, she and Aria may find some answers at the Kahn brothers' party.

A cabin may hold the key to Maya's secrets so Hanna and Emily do some snooping.

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

Unexpected Halloween party guests pop up at every turn and The Rosewood Halloween Ghost Train becomes one killer party.

To the girls' dismay, Mona is headed back to Rosewood High. Aria, Emily, Hanna and Spencer take very different views of the "new" Mona.

A battle of the brains stresses Spencer, Aria learns of reasons to suspect her father of foul play, Hanna confronts Lucas, and Emily gets a fright in the woods.

Ailing Aria has reason to be afraid, while Spencer’s romantic gesture results in an unpleasant surprise.

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

Emily’s memories get muddled in therapy, Caleb’s boyhood things intrigue Hanna, Ezra’s brother brings trouble, and Spencer gets bitter.

Spencer’s misbehaviour causes concern, Hanna engineers an encounter Caleb is resisting, Emily’s detective work turns dangerous.

Det. Wilden seeks to silence those who know his secret, the heat is on for Spencer after reengaging with Wren, and Ezra’s mother tries a new angle of attack.

Death stalks someone close to Spencer, while Hanna has evidence to ditch, and Aria finds baby-sitting awkward.

Spencer’s mental state deteriorates while her friends fret. A reappearance proves miraculous and ominous.

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

A turncoat’s betrayal is nothing compared to the deadly trap the liars are lured into hoping to see the face of their nemesis.