In the season four premiere, the Liars are desperate to uncover what new scheme "A" has in store for them in the wake of the lodge fire, and have no choice but to turn to Mona for answers, now that she is also being targeted. Aria struggles with seeing Ezra in the wake of their breakup, and Emily starts to make plans for life after high school. Meanwhile, "A" sets Toby on a new path, what's in the trunk is revealed, and a shocking discovery reverberates through Rosewood.

Hanna worries that her mother is keeping a dangerous secret and is determined to protect her at all costs, which leads her to an uncomfortable meeting with Detective Holbrook. A clue in Ali's things leads the Liars to a creepy mask maker, who takes a shine to Emily and may have ties to another Rosewood resident. Spencer and Toby continue their search into a painful chapter of Toby's past and Melissa returns to Rosewood. Meanwhile, A targets Emily's mom, leading Aria to make a desperate plea of Ella.

Holbrook's partner, Lt. Tanner, comes to town, intensifying their investigation into the Liars and their possible connection to Wilden's death. Emily panics when her parents come under undue scrutiny due to "A's" manipulations. Hanna bristles when Caleb tries to help her through her this latest crisis, and tries to shift the focus of the police investigation. And Toby finds a new source of information into his mother's death, but it only leads to more questions. Meanwhile Aria has an uncomfortable encounter while out with Jake, and Spencer lays a trap for Melissa.

Spencer and Emily make plans to visit a nearby college, but they have very different agendas for their time spent on campus. Spencer's singular focus in figuring out Ali's apparent connection to the school contradicts Emily's real fears about her plans for after she graduates. And after a stinging attack by "A," Aria and her brother Mike don't see eye to eye regarding what's best for their parents. Meanwhile, Hanna becomes increasingly frantic when she makes another horrifying discovery among her mom's things, leading her to make a desperate move - with disastrous results.

Hanna has some explaining to do to her parents and the police after she’s found with something she shouldn’t have. Mona spills a secret of Spencer’s to the other Liars – leading to hurt feelings amongst the group. Emily tries to help Hanna, only to have “A” turn the tables. And Aria helps out a friend of Mike’s, who gets the wrong impression of her. Meanwhile, Shana keeps popping up in the most unusual places. And Spencer’s investigation into who was on the other end of Ali’s mysterious phone number leads her and Toby to Ravenswood – which is unlike any place they’ve ever seen.

Caleb and Toby team up to investigate “A” and what really happened the night of the lodge fire and encounter a source that points to a new possible identity for “Red Coat.” Hanna struggles to act like everything is normal and her friends are unsure about how to help her. Aria worries about Mike‘s behavior in light of an incident at school and Ezra struggles with how he now fits into her life. Meanwhile, The Liars are determined to find a new suspect in Wilden’s murder and their tactics have unintended consequences. And, “A’s” new plan threatens to send everything crashing down around one of the Liars.

Hanna comes up with a desperate plan to save her mother from a conviction and turns to the only person she thinks can help – Mona. Caleb tries to convince her Mona can’t be trusted, causing Mona to prove her loyalty in the most unexpected way. And Spencer returns to an old haunt to investigate new evidence relating to Wilden and his surprising ties to another mysterious death. Meanwhile, “A’s” recent machinations take their toll on Emily and her mom, driving Emily to reconnect with her old boss Zoe to look for an escape. And Aria relies on Jake to help her understand Mike’s new attitude, leaving them both confused about the nature of their relationship.

Paige throws Emily a surprise birthday party with even more surprising guests – Jenna and Shana. But it’s “A’s” actions at the party that lead to the biggest shock of all. Mona’s selfless act provides Hanna and her mother with their first bit of good news, but sends Mona down a familiar path. And Ezra gets some distressing news from Maggie regarding her and Malcolm. Meanwhile, Aria and Jake continue trying to define their confusing relationship. And Emily meets with a world class coach in a last ditch effort to salvage her swimming career.

Still living at a motel, Emily is taken aback when Mrs. Dilaurentis offers to let her move into Ali's old room and is even more distraught when the other Liars insist she take Mrs. D up on her offer. Hanna explodes when it appears her mother's recent good fortune has taken a turn for the worse. And Ezra continues to reel from Maggie's big news when he's dealt an even more crushing blow regarding his son. Meanwhile, Aria makes an effort to get involved in Jake's interests and finds herself with an opportunity to follow up on a lead. And "A" continues to toy with Toby's emotions regarding his mother's death, and Spencer is along for the ride.

After uncovering recent evidence that suggest "A" is hiding out closer than they realized, the Liars step up their investigation into their most recent suspect. Hanna continues to crumble due to her newfound infamy as the daughter of a murder suspect. To complicate matters, Hanna is being stalked by fellow student Travis until she learns he is hiding a secret that may change her life. Meanwhile, Toby continues to be manipulated by "A," dangling insight into his mother's death. And Ezra tries to reach out to Aria for help in dealing with his recent troubles, right when she becomes more determined to move on with Jake at a Western themed dance that turns into a two-step with "A.

An intriguing riddle from “A” has the Liars hitting the road and heading to Ravenswood, where they are surrounded by some familiar faces. During a very special magic show, one Liar pulls a disappearing act, leaving the other three scrambling to make sure she hasn’t succumbed to “A’s” tricks. But before they can hightail it out of Ravenswood, they make a shocking discovery that proves that everything they thought they knew about “A” and the “A” team might be wrong. With this discovery, the Liars may just have started “World War A”-- #WorldWarA. Meanwhile, Hanna and her mother’s joyous reunion is cut short when “A’s” sights are set on a new target. And Toby uncovers some surprising information about Wren.

Aria, Emily, Hanna and Spencer crash the Ravenswood Founders Day Celebration after finding a clue in "A's" new lair that Ali may indeed be alive. Dressed in their finest Edwardian wear, the ladies hit the creepy cemetery party to find Ali before "A" can. But if Ali is truly alive, could the PLLs be leading "A" straight to their friend without knowing it? With Ezra lurking in the shadows, "A" may be closer than the girls realize. Meanwhile, Caleb heads to Ravenswood to help the girls and meets kindred soul Miranda along the way.

Armed with the knowledge that Alison is alive, Aria, Emily, Hanna and Spencer have more questions now than ever before. Trying to put the pieces together Hanna comes up with the idea that if they find out who is really buried in Ali’s grave it may lead to much needed answers. But as the girls search, Emily has trouble dealing with how she feels about Alison being alive.

Now that Hanna has shared with Aria, Emily and Spencer that she has Ali’s diary, the girls hope it can shed light on their many questions. But with the diary full of stories that have been coded to cover the truth, each girl must take a turn to figure out which stories are about them. Hopefully when they are through they will find the story that could finally give them answers to who has been going after Ali. But with each story more personal than the last, do Aria, Emily, Hanna and Spencer really want to admit which story is about them? Meanwhile, Spencer is suspicious of her father’s latest interaction with Mrs. DiLaurentis.

Shana returns to Ravenswood to tell Emily that she has a message from Ali, but can Emily and the girls trust Shana with all that they know about her? And when Shana ups the stakes and says that Ali wants to meet Emily - and only Emily - could it all be part of an "A" plan, or is Emily really Alison's favorite? With Emily becoming more hopeful by the minute, Spencer is determined to not let her friend get hurt. Meanwhile, Aria and Hanna deal with matters of the heart.

Hanna's new interest in crime novels helps her to come up with a plan to try and figure out whose body is in Ali's grave. While Hanna is on her hunt, Spencer is working overtime to decipher the stories in Ali's diary which she hopes will reveal the identity of Ali's mystery man. But with both girls hot on the trail, will their work lead them straight into "A's" path? Meanwhile, Aria is upset with the new friend Mike has made and Emily's dad is concerned about her behavior.

With Spencer’s possible Board Shorts revelation, she is now more determined than ever to prove her theory before bringing it to the other girls’ attention – especially since it could have a devastating effect on one of the Liars. But with many sleepless nights fueled by prescription medication, Hanna starts to notice Spencer’s odd behavior. Will Detective Hanna be able to figure out Spencer’s secret before Spencer is ready to share? Meanwhile, Emily looks to make amends with Alison through Shana, and all of Aria’s lies start to take a toll on her.

Spencer’s numerous sleepless nights with the help of prescription pills start to take a toll on her as her hunt for Ali and much needed answers continues. As she pours over newly acquired information, her world view takes a black and white turn. Now teleported into the world of 1940’s Film Noir, Spencer tries to come up with the answers she and her friends have been desperately looking for. But in this world of fedora hats, switchboards and 15 cent coffee, can Spencer finally put all of the pieces together that lay in front of her?

Spencer is determined that it is finally time to tell Aria about what she has found out about Ezra, but Emily and Hanna are worried about what it could do to their friend. A wrench is thrown into the plan when Ezra tells Aria about his concern and suspicion of Spencer's recent addiction problem. Now with Spencer's credibility being questioned, can the girls trust what Spencer has been telling them about Ezra -- could this all be a figment of Spencer's tired brain or really just a clever ploy by Ezra to cover his tracks?

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 what to trust, Aria goes looking for answers, not wanting to believe this revelation to be true. While concerned for Aria, Spencer 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. But 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 as she searches for answers about Ezra and Mona. After confronting both, Emily tries to make sense of the heartbreaking situation. Hanna, on the other hand, begins a new search after being confronted by Det. Holbrook and Lt. Tanner with a possible new lead in Alison’s case.Meanwhile, 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.

After years of questions and mystery surrounding the night Alison DiLaurentis disappeared, her four best friends come face to face with Ali and finally learn what really happened to her that September night. Now with their newfound knowledge of Ali’s long-held secrets, can Aria, Emily, Hanna and Spencer help Alison finally figure out who “A” is?