The story then jumps 3 years later, when the girls are living their own lives and don't speak to each other.

Aria returns to Rosewood from a 3-year trip to Iceland with her family and comes back much more sophisticated than before she left. She meets and makes out with a guy in a local bar who is revealed later to be her English teacher, Ezra Fitz.

Emily befriends the new girl in town, Maya St. Germain, and soon develops romantic feelings for her, even though Emily has a boyfriend, Ben. Maya spends more time with Emily, helping her let loose from her conservative lifestyle, however Emily's mother - Kathleen - is racist and so disapproves of their friendship. Ben later finds Maya and Emily kissing in the photo booth at a party and dumps beer on them.

Hanna is the new popular girl in town alongside the former nerd, Mona Vanderwaal, who she is extremely attached to. However, she and Mona sometimes shoplift though both can clearly afford their steals. Hanna is caught and arrested for stealing earrings and necklaces from a jewellery shop. Hanna battles the urge to turn back to bulimia, struggles with living with her absent workaholic mother and to manage the stress of keeping her queen bee status.

Spencer continues to struggle in her long-standing rivalry with Melissa Hastings, her perfect older sister. Problems occur when she begins to feel attracted to Melissa's new boyfriend, Wren Kim.

Throughout the story, the liars get messages threatening to reveal their secrets of the present and past, including a terrifying incident the girls refer to as "The Jenna Thing". They automatically believe it is their missing friend, Alison, because she is the only one each of them confided in regarding their darkest secrets. However, they are shocked when the police find her corpse buried in the gazebo of her former house. The book ends with the liars receiving a text at Alison's funeral saying, "I'm still here, bitches. And I know everything. -A ".

"The Jenna Thing" is revealed to be an incident in which Ali had set off a firework in Jenna Cavanaugh's step-brother Toby's treehouse to get revenge after Toby spied on the Liars changing, only to see the treehouse burst into flames, not knowing that Jenna was inside, and due to that, Jenna was permanently blinded. Toby was framed for the fire by Alison.

"A" sends Emily a text message hinting that "A" knows about Emily and Maya's romantic relationship and threatens to tell everyone about it. Emily becomes close with Toby and goes to a big benefit party with him but then later tells him that she thinks she might be gay.

"A" leaves a note for Hanna that forces her to tell Naomi and Riley that she makes herself throw up and that Sean was the one who broke up with her. Later on, she receives a text that tells her Sean is at Foxy with another girl. Hanna is shocked to discover her former boyfriend Sean Ackard ignoring his Virginity Club vows and nearly having sex with Aria.

"A" continuously tells Aria to either 'get rid of the problem' or to tell her mom the truth about Byron, her father, that he is seeing another woman. Aria goes to confront the other woman, Meredith, but when she does Meredith tells her that she and Aria's father are in love. Ella finds out that Byron is having an affair with a student named Meredith Gates and kicks him out, leaving Ella and Aria's mother-daughter relationship shattered.

Spencer continues to date with her sister Melissa's now ex-boyfriend Wren and loses her virginity to him. However, Melissa starts to hook-up with him as well and eventually makes sure that he will be out of both of their lives for good.

After receiving a text from "A" about Foxy, Hanna realises they are at the party and tells Spencer and Aria. The three believe it to be Toby, but discover Emily has gone home with him after her ex-boyfriend Ben attempted to rape her. Spencer phones Emily, but the two get cut off.

In the car, Emily blurts out many things to Toby, feeling overwhelmed, but he rants about Alison to her and says he is happy she's dead. Scared, Emily flees from the car and runs home where Toby turns up as well and starts banging on the door shouting that he needs to talk to her. This is when she receives the call from Spencer, but she hangs up after spotting Toby. Emily tells him she knows what he did to 'her', meaning killing Alison, and Toby starts freaking out and begs her to not tell the police. The next day, Toby is found dead on the road leading to Emily's house and it's revealed he committed suicide. It is revealed that Toby was forcing himself on Jenna when they were in middle school and Ali and Spencer were the only ones who knew about it, which is how Alison forced Toby to take the blame. A traumatised Emily feels responsible for Toby's suicide as he believed that she knew about him and Jenna.

Now homeless after being kicked out by her mom, Aria goes to live with her new boyfriend, Sean Ackard. Still seeing Ezra, their relationship is broken up when Sean informs the police, having found out the secret from "A". Although the charges pressed against Ezra don't stick, he moves out of Rosewood after being fired from the school.

Emily plans to go to the police to stop "A", which leads to "A" taking revenge by outing her to the whole school. Emily's parents threaten to send her away if she does not attend a "de-gaying" program, however, Emily realizes she can't change who she is.

Spencer is nominated for a Golden Orchid Award for the essay she copied from her sister Melissa, which "A" threatens to expose. Spencer's family discovers she cheated on her Golden Orchid essay, but keep it quiet to protect their reputation. Spencer comes to believe she might have killed Alison after discovering she suffers from rage-induced blackouts.

Hanna and Mona get into a fight, and Hanna seeks comfort with an "uncool" boy named Lucas. She goes to Mona's birthday party but gets humiliated, but she receives a text from "A" and recognizes the number. She intends to reveal the true identity of "A" to the other girls, but is run down by "A" before she can do so. The girls recognize it is A from the eerie text: She Knew Too Much -A

Emily's parents catch her with Maya at a party and send her to Iowa to live with her strict, religious relatives. She is glad to be safe from "A", but after Emily is accused of threatening her cousins, she runs away. Emily returns home when she sees her parents on TV, who tell her that they love her and accept her for who she is. Emily and Maya are reunited, but Trista, a girl who Emily had met and flirted with in Iowa comes to visit, their relationship is shattered, and Emily is saddened further when she sees Trista and Noel hooking up.

After being kicked out of Sean's house, Aria reluctantly moves in with Byron and Meredith, who announces that she is pregnant and when Byron's and Ella's divorce is finalized, they are to be married. While at Hollis College, Aria takes an art class and befriends Jenna, who she suspects could be "A".

"A" reveals to Melissa (Spencer's sister) that Spencer stole her essay for the Golden Orchid competition, but the family keeps quiet to protect their reputation. Melissa and Spencer grow closer, and Spencer confesses that she kissed Ian, and that he and Alison were secretly dating. When fragments of her memory from the night Alison died are restored, Spencer is horrified when it dawns on her that she may have accidentally killed Alison.

Mona and Hanna's friendship is restored, and to celebrate Hanna's recovery, Mona and Spencer plan a party for her. Spencer is surprised to discover that she enjoys Mona's company, and even more so when Mona tells her that she has been receiving messages from "A". Hanna is thrilled that Spencer approves of Mona, and they consider letting her join their clique.

"A" tells Aria that Meredith has a secret job at Hooters, and she goes there with Mike, only to discover that "A" was lying. Darren Wilden and several other cops are there, and Aria is tempted to tell them about "A". When Mike realizes that something is troubling his sister, he urges her to tell Darren, and she eventually does. On the night of Hanna's party, Aria tells Jenna what happened the night she was blinded and apologizes for not stopping Alison, but Jenna reveals that she and Alison had planned it together to get rid of Toby. Aria asks Jenna about "A", but Jenna becomes scared and quickly leaves, hinting that she knows who "A" is.

Melissa confronts Spencer about seeing Ian behind her back, which Spencer denies, and when she leaves, Spencer and Mona discover another note from "A" and suspect that Melissa killed Alison because she was jealous of her relationship with Ian. They inform the others, and decide to turn Melissa in. Mona drives Spencer to the police station, and Aria tells Emily and Hanna the truth about The Jenna Thing. When Hanna says that one in four boys sexually abuse their sister, Emily tells her not to believe everything she hears, which causes Hanna's memory to return, and she is horrified when she remembers who "A" is: Mona.

Spencer is hesitant about turning in Melissa, but Mona comforts her and convinces her otherwise. Moments later, Spencer receives a text from Emily, telling her that Mona is "A". When she receives several more from the girls, who are worrying about what Mona will do, Mona realizes that they finally figured it out. While Aria, Emily and Hanna go to the police station to tell Darren that Mona is "A", Mona drives Spencer to Floating Man's Quarry, where she explains that she saw what happened on the night of The Jenna Thing, and when Maya moved in, she found Alison's diary, which contained the girls' secrets. Using the information to her advantage, she got a new phone and became "A" to get revenge on the girls for blinding Jenna. Spencer accuses Mona of killing Alison, but Mona says that it was Ian who killed her, as Alison had blackmailed him about their relationship.

Spencer secretly calls Darren, who overhears her conversation with Mona and learns of their location. Mona tells Spencer that she originally planned to frame her for Alison's murder, but recently grew to like her, and thus decided to frame Melissa to do Spencer a favor. She then offers Spencer her life in return that she becomes "A" with her, as they could pin the blame on someone else. Spencer refuses and Mona attacks her. They fight on the cliff's edge, and in the struggle, Spencer accidentally pushes Mona off the cliff to her death. Aria, Emily and Hanna arrive on the scene with Darren and police, and find Mona's body and an unconscious Spencer.

Emily finds herself confused about her sexuality once again, as she now has feelings for a boy she met at church, Christian singer Isaac. Emily tries to date Isaac without him finding out about her orientation, though "A" keeps interfering. Emily tells Isaac about Maya and he then hugs her and tell her that he accepts her for who she is.

Hanna, still overcome with shock after discovering Mona Vanderwaal was really "A", can't seem to catch a break. She now has trouble with her stepsister Kate Randall. At a party at a hotel opening, Hanna and Kate continue to fight over title of "Queen Bee". Hanna and Lucas break up after Hanna tells everyone that Kate has herpes at a party to sabotage her. Eventually, Hanna's father forbids her from talking to anyone except Kate. Hanna begins to believe Kate may have been working with Mona, but soon realises that they were just friends and Kate had no idea.

Aria has feelings for a man, Xavier, who she met at an art show; however, he ends up meeting and dating her mother through an online match site, having lied about being younger to Aria. Xavier tells Aria he loves her, but she is disgusted by him. This puts her at risk of hurting her mother again and further damaging their newly repaired relationship. Aria moves in with Meredith and Byron to avoid Xavier as his true intentions will jeopardize Aria and Ella's relationship.

After a shock at her gran's will reading and her family neglecting her, Spencer comes to believe that she is adopted and starts searching a reuniting website for answers. She soon starts dating her class rival Andrew after he helps her find her supposed mother. Ian visits her and insists he is innocent to Spencer's disbelief, he later visits her again after breaking out of jail. A tells Spencer not to tell Wilden about these visits.

In the end, Spencer, Emily, Aria, and Hanna find Ian's body in the woods behind Spencer's house, but when they return with the police, the body is missing.

Spencer meets a woman named Olivia Caldwell who she thinks is her real mother, and attempts to move to New York, but it turns out to be a scam and she loses her college money.

Kate has feelings for Mike Montgomery, who was Hanna's first kiss, and she becomes obsessed with stealing Mike from her, despite hating Mike now. The two ask Mike out on dates and he goes out to them until Hanna embarrasses him. Hanna tells Mike they must be exclusive and he agrees, but tells her that she must take him to prom. Kate reveals to Hanna that she doesn't like Mike and pretended to in order to get Hanna to date him, as she knew they didn't like each other. The two get into a public argument which Mike overhears and runs off, leading Hanna to realise she does like Mike. Noel Kahn helps the two reconcile and they become an official couple. Hanna discovers messages between Wilden and Jason and remembers the two were very close when younger, with Wilden picking up Jason after a particularly loud argument with Alison which Hanna overheard - glass had been smashed.

Aria meets Jason DiLaurentis, her former crush, at a bus stop and the two flirt but Jason suddenly freaks out and abandons her. They later go out to a bar together and kiss. Aria invites Jason to a party at Radley, a children's mental hospital turned hotel, but he accuses her of playing a cruel prank on him and runs away. Later, she receives an email from Jason telling her to meet him at his house, but when she arrives there is no answer and she gets chased by a savage rottweiler through the window. Jason discovers her and accuses her of stalking before kicking her out. Aria sees someone running away into the woods with the rottweiler.

Emily has sex with her new boyfriend Isaac, whose mother finds out and banishes Emily from their house without Isaac knowing. When Emily tells Isaac he refuses to believe her and is rude, however later apologises after discovering the truth, Emily breaks up with him despite this. Throughout this, Emily has constant run-ins with an erratic Jason who almost runs her over and she receives many instructive texts from A who sends her pictures and questions to figure out Alison's murder. At the opening party for Radley, a former so-called "haven for troubled youth", Emily finds proof that Jason DiLaurentis had been a patient there, and soon Hanna, Aria, and Emily all come to believe that Jason and Darren Wilden had something to do with Ali's murder.

Ian Thomas confirms their suspicions through email about Darren and Jason right before someone sets the woods behind Spencer's house to fire. Although at first they had their doubts about Ian being alive, they are now confident he is. While Aria is trying to get to Spencer's barn to show them Ali's flag from 6th grade, she finds someone caught in the woods because of the fire, saves this person, and then they all recognize her as Ali.

"A" sends Emily to an Amish group in Lancaster, under a false identity, where she befriends a girl named Lucy and helps her plan an upcoming wedding. She learns that Lucy's sister, Leah, went missing several years prior after threatening to run away with her boyfriend although everyone - except Lucy - believes her boyfriend murdered her. Emily discovers Wilden was Leah's boyfriend and believes she is the body in the grave not Alison's, and A instructs her to break into Rosewood's police precinct for evidence but she is caught and arrested.

Aria begins a relationship with Noel Kahn, after he defends her at a party. Noel, who believes in psychics, convinces her to go to mediums with him one of which produces a message in Ali's handwriting that states that "Ali killed Ali". This leads her to believe that Ali might have committed suicide. Whilst visiting Ali's grave at the cemetery, Aria is accosted by police and arrested.

Hanna's father sends her to a clinic to prevent her eating disorder from reappearing due to stress, where she befriends a controlling girl named Iris. Iris is obsessed with her previous roommate, Courtney, and insists Hanna be 'normal' leading Hanna to lie about being a 'Pretty Little Liar'. A leaves a newspaper revealing the truth, and Iris reveals Hanna is in a clinic to the press causing rumours that she is clinically insane. Hanna has more dreams about Ali, which causes her to suspect that Iris had something to do with Ali's death, especially when Iris shows knowledge about Ali even Hanna didn't know. Iris threatens Hanna, causing her to break down in front of everyone before she is arrested by the police.

"A" reveals to Spencer that her father had an affair causing her to uncover photos of Alison's pregnant mother, realising they had the affair and that Ali is her sister. A sends more messages, leading Spencer to believe her mother had uncovered the affair on the night of Alison's murder and killed her. At a surprise celebration, Spencer confronts her father only to discover her mother and Melissa had no idea, Mrs Hastings screams at Mr Hastings and demands a divorce. As the night dissolves into chaos the police arrive and Spencer is arrested.

It is revealed the Liars were all arrested for Ali's murder where they realize that "A" has tricked each of them into believing someone else killed Ali. However, a man named Billy Ford is soon arrested for murdering Alison and an unnamed body. Scared it is Melissa, Spencer rushes home to discover Jenna Cavanaugh's body being fished out of their ditch.

'Courtney' flirts with Emily before revealing her identity, Emily's crush on Ali is quickly reignited and she asks Ali about the kiss, Ali admits she likes Emily but begins avoiding her afterwards. Emily asks Ali out as her date to the Valentines Day Dance, but Ali refuses and kicks Emily out of the house. At the dance, Emily grows upset with Ali after seeing her dance with other people and begins to believe she was manipulating her until Ali meets with Emily in the bathroom and kisses her. The two start an unofficial relationship.

Spencer gets to know Ali and they attempt to connect as sisters, becoming extremely close. Melissa doesn't trust Ali and attempts to stop Spencer from talking to 'Courtney', causing Spencer to slowly believe Melissa knows that she isn't Courtney.

Hanna's boyfriend, Mike, has items planted in his locker causing a mockery to be made of him in the entire school, when given a choice between Mike and her popularity, Hanna dumps and publicly shames Mike for a chance at re-joining Naomi's clique. Ali reveals herself to Hanna and the two plan to embarrass Kate, Naomi and Riley using messages they wrote whilst drunk. It works, and Hanna tells Naomi and Riley it was payback for dumping Ali out of their group years prior and causing her to befriend the Liars, but the pair reveal Ali was the one who dumped them.

Ali meets Aria at a spot only they knew about and reveals her identity, but unlike the others Aria becomes overwhelmed by the revelation and leaves. Aria tolerates Ali, but begins to believe she is just waiting to embarrass them as she did before, after Ali invites her and the other girls around to prepare for the dance, Aria remembers all of the awful things Ali had done before her disappearance and refuses. At the dance, she hears rumours that Ali and Noel got together and Ali suddenly slaps Noel and accuses him of kissing her, an upset Aria breaks up with him.

After the dance, Ali invites the others around to her house and they all accept. On the way there, Spencer gets a frantic call from her mother telling her that Melissa has disappeared. Spencer had begun to believe that her sister was the one who killed Ali and that she may be after the rest of them, but once they arrive at the house it's revealed that Ali is the killer. They discover that the girl they were friends with years ago was actually Courtney, and the real Ali was stuck in an institution. She had killed Courtney for ruining her life, attempted to kill the girls in the forest fire, tried to have them arrested, and is now going to kill them by setting the house on fire.

They're able to escape after stumbling onto Ian's body hidden in a closet and releasing a bound Melissa, who Ali had kidnapped and was planning to kill as well. Emily is separated from the others in the chaos and is found by Alison, the two engage in a fist fight which Emily wins. Ali is trapped inside the house and it's assumed she died in the fire, although her body is never found.

After learning that her ex-husband shipped Hanna off to a mental institution, Ashley Marin transfers back to Rosewood and kicks Hanna's father, Isabel and Kate out of the house, thrilling Hanna. Hanna and Mike get back together.

Meredith goes into labour, giving birth to a girl named Lola. Aria and Noel get back together after it is revealed that Ali kissed him, not the other way around, and Ella breaks up with Xavier after learning of his inappropriate behaviour towards Aria.

Spencer's father proclaims that even though he and her mother may not get back together, things are going to change for the better in their family, and Spencer and Melissa grow closer after almost being killed. Spencer and Andrew's relationship also strengthens after Ali's attempt to break them up failed.

Emily buries everything she can find that reminds her of Ali at Courtney's grave, hoping she can finally find closure, but is unsure of whether the noises she hears at the cemetery are real or imagined. And somewhere, a new girl starts her senior year at an anonymous school, a girl whose name just so happens to be an anagram of Alison DiLaurentis. The reader is left wondering if Alison is alive.

In the meantime, Noel, Aria's boyfriend, has an exchange student, from Finland, come to live with him. Instead of being the nerdy boy, Klaudius, that Noel expected, the exchange student turns out to be a gorgeous blonde, Klaudia, who tries to steal Noel from Aria. Aria ends up accidentally pushing Klaudia off of a ski lift as an act of self-defense; however, Klaudia uses that information against Aria. By that point, Aria and Noel's relationship is shaky and uncertain.

Emily meets a new girl, Chloe, who moves into the Cavanaugh's old house. They immediately become good friends, bonding over Chloe's baby sister, Grace. Emily has now given up hope of getting a swim scholarship, her only option for college. Chloe's dad offers to help but also hits on Emily, even making sexual moves towards her. Chloe walks in on her dad kissing Emily, but thinks that it's Emily who is wrecking her family (her father had previously been cheating).

Hanna's dad runs for senator of Pennsylvania. Patrick, somebody who's helping out at the set, offers Hanna a modeling job, but he takes some naughty pictures and threatens her with them, saying he will release them to the public and ruin her dads' chances of becoming senator, unless she gives him $10,000. Hanna steals money from her dad and frames Jeremiah, a mean man who is also working on set.

Prior to the beginning of the book, Andrew has dumped Spencer after being unable to handle the press consistently hounding him. Spencer's mom has begun to date Nicholas Pennythistle, the father of snobby Amelia and her brother Zach, in whom Spencer develops a romantic interest. When they go out dancing, she kisses him, only to find out Zach is gay. When the Hastings and Pennythistles travel to New York together, Spencer and Zach drunkenly fall asleep in the same bed. During the night, Spencer had kicked off her clothes because she was hot, leaving her in her blouse and underwear. The next morning Mr. Pennythistle wakes them both up by entering the room. Their indecent clothing and close proximity leads Mr. Pennythistle to believe that they had slept together and acts violent. Spencer tells him that Zach didn't touch her and that he's gay, hoping to help, but Mr. Pennythistle becomes furious and sends Zach to military school. Zach and Spencer's friendship ends, Zach leaving Spencer with the words "Rot in hell, bitch".

The girls start to get messages from a new "A", and believe it's Ali and that she somehow survived the fall from the building. In the end of the book, the news turns on and a teenage girl's dead body was found floating in the water in Jamaica. They identify this girl as Tabitha Clark from New Jersey. The cops believe her death was a tragic accident - not a murder. The girls realize they killed an innocent girl.

Emily accidentally meets Kelsey at a party and is instantly smitten with her. She and Kelsey grow close, much to Spencer's disapproval. After Emily is hurt by Spencer's remarks about her love for Alison, she angrily tells Kelsey that Spencer framed her for the drug possession. Depressed, Kelsey overdoses and attempts to throw herself into the quarry where Mona died, but Emily saves her and Kelsey is sent to the Preserve for treatment. While visiting Kelsey, the girls realize that Tabitha was also a patient at the Preserve and was the same age as Alison and Courtney.

Hanna's father asks her to help with the social media aspect of his campaigning. She meets a boy named Liam, who she falls for, despite knowing he is the son of her father's political opponent. They break up when she learns he has been seeing multiple other girls while dating her, and reconciles with Mike.

After Aria is dumped by Noel, she seeks out comfort in Ezra, in hopes of rekindling their romance. However, things are strained between them, and Aria eventually goes back into a relationship with Noel, after discovering Ezra and Klaudia being intimate.

The Liars attempt to circumvent "A's" threats by coming clean about their secrets, with varied success. Meanwhile, "A" becomes more violent, shoving Emily down a hill at Stockbridge trail. "A" sends Spencer an email of Tabitha on the beach with a head injury, indicating that "A" was the one who disposed of Tabitha's body. "A" taunts the Liars, stating they will never discover "A's" true identity. Kelsey cannot be A. Emily and Spencer have their biggest rivalry.

Spencer visits Princeton hoping to join an Eating Club, but "A" interferes and spikes Spencer's pot brownies with LSD and Ritalin and a member named Harper is caught with pot, which she attempts to blame on Spencer.

Aria panics when she finds out Noel's father is a drag queen and ends up putting her relationship with Noel at risk when "A" threatens Aria to expose Noel's father photo publicly.

On a tip from "A", Hanna begins spying on Mike's new girlfriend, Colleen. Later she becomes publicly humiliated by "A" when she sends everybody a video of Hanna stalking Colleen, and her desperate ways of getting Mike back.

Gayle is murdered by "A" and it is revealed that she was Tabitha's stepmother. Tabitha's father speaks at Gayle's funeral, and announces that Tabitha's autopsy showed no trace of alcohol, meaning that she was murdered. He thus plans to re-open the investigation into her death, and threatens the killer that he will find him, both Gayle's and Tabitha's killer. The girls get very nervous about this.

After an explosion on the boat, the Liars go off on their own to bury "evidence" of their connection to Tabitha (Tabitha's locket, which "A" had planted for Noel to find). "A" tampers with their lifeboat, nearly stranding them in the middle of the ocean. The near-death experience pushes the girls into wanting to confess about killing Tabitha. However, as they make plans to come clean about everything, they discover that they were not responsible for Tabitha's death at all: She had been bludgeoned to death by "A".

The Liars finally come to believe that "A" is, in fact, Alison, as Emily reveals that she may have helped Alison escape the burning Poconos house in Wanted, and now they have to track down her accomplice as well.

Emily tries getting information of out of Ali's old friends, Iris, (who we met in ''Heartless). Iris tells Emily little tidbits of Ali, and at Prom Iris recognizes Noel and for sure he was Ali's secret boyfriend who visited her. Spencer finds an internet blogger, who blogs about Alison DiLaurentis theories. She meets him and actually ends up liking him, finding his name is Chase. He helps Spencer get information on Alison. Hanna, in an attempt to get information on a burned victim from the last book, Graham, starts volunteering at the Burn Clinic. There, Graham is still in a coma and right when he's about to wake up, he dies -all the information is kept hidden for good. Aria, worried and paranoid about what happened last summer, is trying to handle things with Noel being A, even though she doesn't want to believe it. At Prom, Noel admits to loving Ali, and Aria, furious, freaks out and asks Noel if Ali is still alive. He says he doesn't know. While Aria is attempting to get away, Noel pins her to the ground. Spencer, Hanna, and Emily arrive and Noel flees. The morning later, Hanna gets a text from A saying to go to the shed in the Rosewood Day back. She and the three other girls go, and just in case bring Cops and police and inside is a supposedly unconscious Noel tied up to a chair. It is not revealed if Noel is dead or alive. The girls get a text, signed by A, informing them that they've failed to make progress, Noel wasn't A, and they are back where they started.

As a result of telling the police, "A" gave the police a fake security video of the girls beating up Tabitha before she is killed. The police arrest all of them and told the girls that all of the texts from "A" had come from their phones. The girls are put on bail and go home. Emily's family seem to hate her and Emily and Carolyn get into a fight. As this happens Emily's mom has a heart attack. Hanna's father wants nothing to do with her because it will hurt the campaign. After their hearing they are sentenced to go to trial in Jamaica the next day. Certain to find "A" they go searching. They find a house by Hanna's father's office and go inside. It is small and disgusting. As they are walking in Nick Maxwell comes in pointing a gun at the girls. He is "Helper A" Real Ali's boyfriend. The girls all know him as someone else. Spencer knows him as Phineas, a guy at Penn's summer program who sold her study drugs. Hanna knew him as Jackson, the bartender who kept on giving Madison drinks and refusing to get a cab, resulting in Hanna getting in a wreck with Madison. Emily knew him as Derrick, a friend she had at her job, telling him all of her secrets. And Aria knew him as Olaf, a guy she stole The Starry Night with while vacationing in Iceland. Right as they realized what was happening Alison shows up with a gun and tells the girls to get in the basement. They girls do as they are told and the go down. They see a mural of Ali on the wall and they are confused. Ali tells them that after she kills them that it is going to look like they did it to be with Ali because they were sad that she was gone. Astonished the girls ask questions. After, Nick and Ali grab gas masks and turn on a poisonous gas. They girls awake in the hospital and Agent Fuji tells them that Nick Maxwell was caught but not Ali. In the epilogue Ali is running away and goes to a little house that Nick didn't know of. She has money and reveals that she is going to lure someone else to kill with her again.

Hanna is invited to play Naomi in a movie about the liars' lives entitled 'Burn It Down'. The actress playing Hanna, Hailey Blake, photographs the actor playing Mike making moves on Hanna before kissing her. Hailey is fired from the set after giving many terrible performances in the role and Hanna, seeing an opportunity, suggests herself as Hailey's replacement to the director. In an act of revenge, Hailey sends the photos of Hanna and her co-star to TMZ, exposing Hanna to Mike. Later, after seeing clips of her acting performance, Hailey realizes she was terrible in the part. She apologizes to Hanna and explains the situation to Mike, who takes Hanna back.

Emily's girlfriend Jordan, who is in prison, is told by her lawyer there is a way to leave on parole and both are ecstatic and begin making plans for a future together. Whilst doing laps in the pool, Ali appears and insists Emily declare her love for her, which Emily refuses; Alison attempts to drown her and nearly succeeds. Alison runs off when Emily manages to climb out of the pool, but Emily snags Ali's hoodie in the ensuing scuffle, where she finds a receipt from a market in a nearby township. Terrified, Emily attempts to call Jordan in prison but receives some shocking news - Jordan has been found dead in her cell. Another inmate who escaped from the prison is suspected, but Emily knows that Ali did it because Emily rejected her. A few days later, the suspected inmate is also found murdered. Jordan's death sends Emily into a bad place and she starts sleeping on the floor of her closet as well as considering going after Ali.

Using the receipt Emily snatched, the girls track down a pool house on one of Nick's parents' properties that they believe Ali had been hiding out in. They set up cameras in an attempt to catch footage of Ali, however a traumatized Emily breaks into the house one night and destroys everything. Despite cleaning up the mess, the cameras still recorded her melt down, including vague threats of violence Emily had been making towards Ali.

Spencer starts a Bullying Forum Website to help people who are being bullied and becomes reasonably well known for it. However, a group of crazed Ali fans, calling themselves the Ali-Cats, start harassing Spencer, particularly one named Dominick. Spencer then meets Greg, a fan of hers who she supposedly helped out of a bad place, and begins to fall for him. Spencer tells Greg about how Ali is alive and inadvertently reveals the cameras they set up to spy on Ali, only to discover he is an Ali-Cat hired by Alison herself to infiltrate the liars and she had given him useful information.

During an event to honor disadvantaged Rosewood youth, all the girls leave early to return to the pool house to find it covered in blood. While canvassing the house, they are met with an overwhelming smell of bleach and find the blood mysteriously cleaned. Agent Fuji turns up the next day and while they attempt to explain away Ali's crimes, Fuji reveals they've been implicated through their behavior and DNA analysis in the torture and murder of Alison.

The liars visit Nick in jail, he tells them that Alison may be at his grandma's house. The liars drive out there but discover nothing. they decide to spend a night in a nearby hotel before the trial the next day.

The next chapter goes to Emily, after writing a suicide note for the girls to read she ventures out to sea where she believes it may be happy. Spencer tries to save her however she just gets injured herself. Emily is then pronounced dead.

At Emily's funeral, Hannah, Spencer and Aria turn up against Mr and Mrs Field's wishes. Hanna and Spencer get into a huge argument, eventually Aria gets involved and the three end up blaming Emily's death on each other and saying extremely hurtful things.

Spencer then has lots of hospital appointments where she finds herself meeting her ex-boyfriend Wren. Wren apologies for cheating on her in the past and although she tried to resist, she started to fall for him again.

After realizing that his girlfriend could be facing prison for life, Mike decides to propose to Hanna and they begin going crazy trying to plan a fabulous wedding in such a short space of time. The girls are fitted with trackers on their legs, but Aria makes a run for it and flees the country.

With Spencer and Hanna arguing and Aria on the run, The Liars start to look guiltier than ever. Ideas begin to form in Spencer's head about running away, like Aria did, she then steals some of her mother's jewels after Melissa reveals she pregnant and her parents get mad at Spencer and contacted someone to help her run away.

Meanwhile, Noel manages to find Aria and they begin to stay off the radar together. However, on their way to Japan, they are caught and return home in time for Hanna's wedding.

Hanna starts to miss her friends, even as much to order Aria, Spencer and Emily headbands to wear to her wedding, she also finally stands up to her father and uninvites him from her wedding. At the wedding she and Spencer, who has started a relationship with Wren despite her plans to leave town, make up and the remaining liars are reunited.

After being stopped from running away by Wren, Spencer is called to court where she meets Aria and Hanna who had been called also. There they meet with the lawyers and, to their complete shock, a very proud and alive Emily.

The book then cuts back to Emily before writing her suicide note. Struggling to sleep in the motel, she goes back to Nick's grandma's house where she finds an envelope addressed to "Day" with an address on. A plan forming in Emily's mind, she wades into the ocean and fakes her death. Feeling upset for leaving her friends, yet overjoyed for being now being a few steps ahead of Ali, Emily travels to the address where she then finds Mrs. Dilaurentis. Realizing that Mrs. D had been protecting Ali and putting all clues together Emily called the police and began a conversation with Mrs. D about how she knew she was keeping Alison hidden in her home. This led to Mrs. D and a slightly overweight and brown haired Alison getting into a heated argument where Emily is threatened with a gun, however Emily manages to fight both off Ali and her mother just in time for the police to come and arrest Alison.

Then, cutting back to The Liars reuniting with Emily, they then see Alison being arrested and find out that they are free.

The epilogue then skips 6 months. Spencer is still with Wren and they are happy. Aria and Noel's relationship has been mended. Hanna was given her role back on Burn it Down and all the girls are seen at the premiere. Emily is still emotional but with Alison in prison she no longer needs to worry and finally cuts ties with her family. The girls are seen having fun with their "A" free lives, living as innocent people, going to school and living with their significant others.