Based on the Pretty Little Liars series of young adult novels by Sara Shepard, the series follows the lives of four girls — Spencer, Hanna, Aria, and Emily — whose clique falls apart after the disappearance of their queen bee, Alison. One year later, they begin receiving messages from someone using the name "A" who threatens to expose their secrets — including long-hidden ones they thought only Alison knew.
After Hanna’s shocking abduction by “Uber A,” the PLLs and company desperately race against the clock to save one of their own. The only way to do this is by handing over evidence of Charlotte’s real murderer to “Uber A.” In order to do so, the girls must decide what blatant lines they are willing to cross that they have never breached before; and once they cross that line, there is no turning back.
With the fallout of Hanna’s abduction still weighing heavily on the PLLs, the Liars begin to grow suspicious of Elliott Rollins as Ali’s condition worsens. Tensions rise between Liam, Aria and Ezra as they work on the book together. Spencer and Caleb are on edge, as neither of them want to talk about the awkward elephant in the room. Meanwhile, Emily receives a disturbing phone call and tries to find a way to see Ali.
Still reeling from the trauma of Hanna's abduction and dark fate, the Liars must shift their focus to another one of their own. In order to protect Alison from Uber A's threats, the PLLs snap into action at a chance to rescue her from the hospital. However, in doing so, they make a deadly mistake that changes everything.
The PLLs desperately attempt to cover up their secret, and in turn, end up straining their relationships with their respective bed buddies by keeping them in the dark. While the aftermath of Haleb’s kiss weighs on Spaleb’s relationship, Spencer copes in ways she might later regret. Mona intervenes with the cover-up plan, for better or worse.
Jenna returns to Rosewood and befriends another one of the Liars’ enemies, making her the PLL’s number one suspect for Uber A. In order to leave the psychiatric hospital, Ali must be released into the care of a relative, leaving her under the suspicious watch of Mary Drake. Spencer enlists Hanna’s help to search for Caleb as he’s missing in action. Aria and Emily stumble upon a secret apartment they hope will lead them to more answers.
The Rosewood P.D. begins to unravel the Liars’ cover-up, which leads them to question Rollins’ death altogether. Hanna deals with an inward battle on whether or not to tell the cops the truth, while Ezria struggles with an awkwardness in their relationship. Jenna reveals part of her plot and a new partner she is in cahoots with. Ali learns that the Liars gave her up as Charlotte’s killer in order to free Hanna, which does not go over well. Meanwhile, someone is murdered for playing with the wrong team.
Jason returns to town to stop Ali from getting too close to Mary. The girls learn something new about Mary and Mrs. DiLaurentis that leads them to a storm cellar full of clues. Ezra gets a call about someone in his past that could change his course. Noel Kahn grows more and more suspicious and rises to the top of the list of suspects for Uber A.
Emily goes up for a position as the Rosewood High swim coach, only to learn that her ex-girlfriend Paige is also up for the job. Hanna is visited by Mrs. Grunwald after she has a vision that the PLLs are in danger. The girls track down the doctor who delivered Mary’s baby in order to get answers. Ali decides to go back to work to help bring some normalcy to her life again.
One of the PLLs goes rogue to prove that Noel Kahn is Uber A, while the others try to find evidence to back her theory and worry about her emotional state. Emily unexpectedly turns to Paige for comfort in her time of need, which causes tension in her other relationships. Jason and Aria team up to look into Mary’s past and what she might be hiding.
The Liars face off with their enemies in a chaotic fight that ends fatally. One of the PLLs learns a secret about her past that changes everything while another Liar discovers something about her future that could alter her course forever.
Spencer focuses on learning more about her connection to Mary Drake, while Aria and Ezra figure out what their future may hold now that Nicole is back in the picture. Mona helps Hanna get her fashion career back on track, and Emily struggles to balance things between Ali and Paige now that the three of them are working at Rosewood High. Meanwhile, A.D. has a special delivery for the Liars, one that reveals the final endgame.
Emily butts heads with teenager Addison, who appears to be a new version of high school Ali, and who may be connected to a familiar foe. Spencer confronts her mother about keeping family secrets. Aria confides in Holden about her relationship with Ezra, while Spencer turns to Detective Furey for help. And Jenna stirs up even more trouble when she returns to Rosewood with some insight into Noel Kahn and recent events.
Hanna is sure Jenna is to blame for a recent professional setback and is forced to bring Caleb up to speed on current events. Aria and Emily team up to investigate Sydney for more information about Jenna and her connection to A.D. Spencer grows closer to Detective Furey, while Aria struggles with her current situation with Ezra. Hanna’s turn at the game is more intense than she bargained for and leads to shocking consequences.
Ali’s turn at the game forces her to face a monumental personal decision, made even more difficult when A.D. triggers Ali to remember a forgotten trauma. Spencer has a long overdue conversation with her father about his past sins and recent whereabouts. Emily continues to navigate working at Rosewood High with both Ali and Paige, especially when Ali comes to a troubling realization about her pregnancy, and Paige makes a big decision. Aria continues to question the fate of her relationship with Ezra and bristles under A.D.’s taunts. And, in the search for Mary Drake, Hanna and Spencer run into a familiar face with a shocking secret.
After being blackmailed by A.D., one of the Liars begins to supply info to the dark side in order to protect those closest to her. Detective Furey questions how much the PLLs know about what happened to Archer Dunhill. Aria tries to issue an ultimatum to Ezra in regards to Nicole, while Emily struggles with how to support Ali. Spencer goes to elaborate lengths to meet up with Mary Drake and encounters Wren. After learning something surprising about Lucas, Hanna sets out to prove her friend is innocent and uncovers even more troubling info.
As Detective Furey closes in on uncovering what happened to Archer Dunhill, the Liars team up to protect one of their own. Hanna continues to struggle with the idea that Lucas might be connected to A.D. even in the face of more evidence. Emily surprises Ali with a heartfelt gesture that is undone by A.D. machinations; and the Liars gain insight into where the idea for the game originated.
With Mona making inroads in the game, Emily reluctantly teams up with her to investigate. Ashley returns to Rosewood to check on Hanna after learning some frightening information and asks Caleb what his intentions are with her daughter. Meanwhile, Spencer’s family reels from A.D.’s latest taunt, leaving Spencer more confused than ever about who to trust. Ezra notices Aria’s change in attitude and fears he may have lost her; and A.D.’s machinations cause Aria to have a terrifying nightmare.
The Rosewood PD turn up the heat on the Liars, causing loved ones to try and close ranks. Aria’s recent collaboration with A.D. comes to the attention of a surprising source. A.D. presents the PLLs with a choice designed to drive a wedge between them. Meanwhile, everyone tries to find a bit of happiness before all hell breaks loose. Toby returns to Rosewood, and Aria makes a horrifying discovery.
Convinced they know who A.D. is, the Liars gear up for a confrontation. Spencer, Hanna, and Caleb team up to investigate and discover new information about Charlotte’s death. Meanwhile, Mary Drake returns with a gift for Spencer and Alison.
All is revealed as the ultimate endgame comes to light.