In the third-season opener, the girls reunite after a summer apart and struggle to move past Mona's revelation and Maya's death. Before long, another surprising event rattles the town.
A new "A" toys with the girls, using elevated stakes. Spencer and Hanna investigate this new foe, who turns one of Aria's past mistakes into ammunition and whose fearful actions have put Emily in a fragile state.
Spencer is curious about why Garrett is her mom's client, so she investigates and uncovers a family secret. Elsewhere, Emily receives unexpected news about her English test; and Aria has an ulterior motive for assisting Jenna.
Caleb doesn't understand why Hanna is visiting Mona, and this tempts Hanna to tell him the truth. Meanwhile, Aria considers sharing details about her dad's dating life with her mom; Spencer seeks answers about Melissa; and Emily meets Maya's cousin.
Aria and Emily search for "A" at Jenna's lavish birthday party. Meanwhile, Spencer keeps an eye on Garrett, who's out of jail visiting his sick mother; and a brokenhearted Hanna uncovers a surprise.
Hanna attempts to find out who's assisting Garrett. Meanwhile, Spencer seeks Jason's help; Emily has another flashback, which points her toward a suspect; and Aria wonders why Ezra is suddenly rolling in dough.
A conversation with a detective leads Hanna to think she's being framed by "A," so Aria seeks assistance from Mona. Elsewhere, a person from Ali and Jason's past shows up in town unexpectedly.
Emily seeks answers about the night she was drugged, and she tries to reconcile with Paige. Meanwhile, Aria meets Ezra's mom and gains insight into his past; Hanna attempts to help Mona; and Spencer asks Caleb to hack into a Web site for her.
Spencer and Aria attend the Kahn brothers' party and engage in an intense game about truthfulness with Jenna. Elsewhere, Hanna receives another text regarding Caleb from "A."
Hanna and Emily seek clues about Maya at the Kahns' cabin in the woods. Meanwhile, Spencer investigates Noel; and Aria tries to process the details she's learned about Ezra's background.
Spencer uncovers Paige's violent past with Alison and warns Emily about her, but Emily is reluctant to take her advice. Meanwhile, Aria attempts to help Ezra put his past behind him, but this proves to be more difficult than she anticipated.
Maya's murder trial gets underway, and Emily can't withstand the media attention surrounding it. "A" then extends an olive branch to the girls, who are skeptical about the sincerity of this offer; and someone close to the girls betrays them.
The girls attend a Halloween party on a train, where they encounter unexpected guests, as well as surprising tricks from "A."
Mona is released from the sanitarium and returns to school, but she faces an uphill battle in which she must prove to Hanna, Aria, Emily and Spencer that she has transformed and can be trusted.
Aria, Emily and Spencer think Mona has regressed to her old bad behavior, but they have no proof, and Hanna has doubts about their claim. Meanwhile, Aria's suspicions about her dad intensify when something important vanishes from her room.
Meredith takes care of an ill Aria, but Hanna and Emily are suspicious of Meredith's motives. Elsewhere, Spencer arranges a surprise for Toby on their anniversary.
Aria wants to tell Ezra about his son, but she worries that the news might damage her relationship. Elsewhere, Hanna is convinced that Caleb is keeping a secret from her; and Spencer decides she's done with game playing.
The girls are divided about going to Ali's memorial service. Elsewhere, Emily deals with unresolved feelings about Nate's death.
A heartbroken Spencer directs her anger toward Mona. Meanwhile, Hanna tries to reunite Caleb and his dad; Aria bonds with Wes; and Emily and Jason attempt to figure out what happened on Ali's trip to the Jersey Shore.
The girls look into Det. Wilden's background, but he finds out and tries to stop them. Meanwhile, Spencer seeks support from a friend.
Hanna helps Ashley in the wake of her mom's hit-and-run and ponders if "A" was involved in the incident. Meanwhile, Emily is not receptive to Spencer's warnings; and Aria must accept Ezra's new role as a father.
Aria, Emily and Hanna search for Spencer, unsure if she went off on her own or if "A" is behind her disappearance, and their concern grows when they discover Spencer's family has no idea where she is. Meanwhile, Emily meets Olympian Missy Franklin.
Emily wants to help Spencer by proving her wrong. Meanwhile, Spencer researches Mona's stint in the sanitarium; Aria has doubts about her relationship with Ezra in light of his parental obligations; and Hanna is forced to deal with Caleb's family drama.
In the third-season finale, Spencer returns home and claims she's fine, but her friends have doubts about whether she's fully recovered. Meanwhile, surprising revelations surface.