The PLLs work with Mona to try and get some clarity on A.

Hanna worries her mother is keeping a dangerous secret, which leads to an uncomfortable meeting with Detective Holbrook; Melissa returns to Rosewood.

A new detective means new questions, and the liars are asked some hard questions; Spencer lays a trap for Melissa.

"A" goes after Hanna in an unexpected way; Spencer works overtime to decipher the stories in Ali's diary; Aria is upset with the new friend Mike has made.

Spencer's hunt for the truth takes a dangerous turn. Will Hanna be able to figure out Spencer's secret?; Emily looks to make amends with Alison through Shana.

Emily, Hanna and Spencer are concerned for Aria as they watch their friend crumble after learning shocking news about Ezra. Not knowing what is true or who to trust, Aria goes looking for answers, not wanting to believe this revelation to be true. Spencer is concerned for Aria, but she is not doing so well herself. Trying to prove to her parents and Toby that she can kick the habit on her own, Spencer has to be careful because one misstep could send her to rehab. Can Spencer really rein it in, or will her constant curiosity and drive be her undoing? Meanwhile, Paige has had enough with Emily's secrets and is determined to stop it.

Emily takes up the sleuthing reins and hunts for answers about Ezra and Mona; Hanna begins a new search after being confronted by Holbrook and Tanner; Spencer and Aria lean on new men in their lives to recover.

It is a rough time for all of the Liars as Spencer is reeling about the memories from her "lost summer," Aria is still nursing a broken heart, Emily is reeling from Paige's betrayal and Hanna unsuccessfully attempts to wade back into the dating pool. But as each girl tries to deal with her individual issues, they must focus their attention on their suspicions surrounding Mrs. DiLaurentis. Assuming that Mrs. D knows more about Ali and the night she went missing, girls decide to help out at her charity bridal fashion show to gain access to the DiLaurentis house to search for answers. Meanwhile, Ella and Jason return to Rosewood, each with something to hide.

The liars finally get answers about the night Ali disappeared. With their newfound knowledge of Ali's long-held secrets, can they figure out who "A" is?

The PLLs must dodge their dreaded nemesis, "A," while navigating a world with Alison back in it.

The liars try to wrap their head around the new normal; Jason's odd behavior and Kenneth's search for Jessica starts to raise eyebrows.

The girls join forces with Mona to figure out why Ali reached out to the police. Alison's actions put Spencer in the cross-hairs of Bethany's murder investigation. Mona reveals the truth about Ali, resulting in an aching loss.

It is Christmas time and all of the liars are planning on having a great time at the Ice ball, but 'A' has other plans.

Spencer spends time with Jonny; Emily tries to figure out Talia; Hanna digs into the past of Mona's friend Lesli; Mike's behavior concerns Aria; Holbrook returns to Rosewood.

Aria hopes Andrew can be her tutor; Spencer helps Jonny with a new project; Hanna turns to her father for financial assistance; Mike is involved in an incident at the school blood drive.