Moments after where the season four finale left off, Aria and the Liars are reeling from Ezra's shooting at the hands of "A". The five girls quickly realize that as the one person who truly knows A's identity, Ezra is in grave danger. While Aria stands watch over Ezra at the hospital, Alison and the PLLs lay a trap to finally flush out "A" but are shocked by who is ensnared. Meanwhile, Holbrook steps up his efforts to find the girls and puts the Hastings family on alert. And as news of Alison's resurrection spreads, Mona is not pleased.

With the events of New York behind them and back in Rosewood, the Liars are unsettled to still be living under a cloud of secrets. Aria is haunted by the recent past events, while Emily, Hanna and Spencer try to wrap their head around the new normal. Alison, on the other hand, is still sleeping with one eye open as she is forced to stay at home with her family - who she doesn't trust. Meanwhile, Jason's odd behavior and Kenneth DiLaurentis' search for Jessica starts to raise eyebrows about her disappearance.

Alison struggles with the passing of her mother, as the Liars try to navigate through her new lie. Now being forced to live through Ali's latest lie, Aria, Emily, Hanna and Spencer try to cover their tracks, while simultaneously trying to piece together what happened in New York. Hanna and Aria have to close loose ends with the two people who know the truth about Ali's story - Mona and Ezra. Spencer and Emily try to find out the truth about Jason and his whereabouts the night they were in New York. Meanwhile, Hanna starts to examine who she really is - Hefty Hanna or Queen Bee Hanna - now that Ali is back.

With Ali now back in Rosewood, she attempts to regain the role of leader of the group, but she finds her four friends are not as willing to blindly follow her every whim as they once were. Besides feeling the pressure from Alison, Aria, Emily, Hanna and Spencer are also feeling under the microscope at school with the high school focusing their attention on the Liars. While most kids are morbidly curious about what happened to Ali, some are more focused on planning for Ali's return to school. Meanwhile, Aria's depression continues to spiral, and she looks for comfort from an unlikely source.

The day has finally arrived - Alison's first day back at Rosewood High, and neither the PLLs nor Alison are really ready for it. Determined to put on a brave face, Alison returns to also help heal the damage she did years ago. But are apologies enough for those who Alison has hurt in the past? Not if Mona and her army have anything to say about it. Meanwhile, Caleb and an old foe return to Rosewood.

With the town of Rosewood trying to get back to normal, the PLLs - especially Ali - are far from okay after the latest "accident". Thinking that it wasn't the right decision to come home after all, Ali starts to consider leaving for good. But Aria, Emily, Hanna and Spencer are determined to keep her safe in Rosewood and to figure out who and what is behind this latest incident. Meanwhile, Caleb also starts second-guessing his return, and Ezra dives into his research to help find answers.

Aria begins her volunteer work at Radley and quickly gets down to business finding any answers she can about a patient of interest to the Liars. But she quickly hits a snag when she comes across an aggressive patient that may be the key to what the Liars are looking for. Also searching for answers, Spencer takes a note from Ezra's play book by borrowing some of his spy equipment to keep a closer eye on the home front. Meanwhile, Hanna is caught at odds when Ali and Caleb butt heads, and Emily seeks help from her friends when her mom invites Ali over for dinner.

Hanna's insecurities and current situation continue to plague her when Alison moves into the Marin house while her Dad is out of town. Now forced to live with the one person she is trying to avoid, Hanna retreats further into abusing alcohol and ends up in a sticky situation. Meanwhile, Aria drops the ball on her maid of honor duties when Ella returns to town to plan her wedding and Spencer and Emily pursue a dangerous lead, trying to solve the mystery of the dead girl in Alison's grave.

Hanna continues down her boozy path, with the help of Caleb, and her friends can no longer stand by and watch Hanna self-destruct. After her last encounter with Hanna, Aria starts to take note of Zach and wonders if Hanna - while drunk - was telling her the truth.Meanwhile, Emily tries to find information linking Alison to Noel and Spencer makes a surprising discovery at the eye doctor.

The pressure is on for Alison to identify the man police have in custody for her kidnapping, but the Liars know if she does it would be sending an innocent man to prison and possibly walking right into an "A" trap. With Emily trying to convince Ali not to play into "A's" hand, Spencer comes up with a plan B in case Ali decides to make the wrong decision. Meanwhile, fed up with all of the Ali drama, Hanna tries to lead a "normal" teenage life.

Melissa finally tells Spencer what she knows regarding the night Ali disappeared. But what is Spencer supposed to do with the knowledge? Knowing something is off about Alison's story, Emily is on the hunt for answers on her own. She enlists Ezra's help in finding out more about Cyrus and his past connection to Alison. Meanwhile, Hanna asks Spencer and Toby for help with Caleb's drinking problem.

With Alison leading them down a dangerous path and "A" barring them from telling the police the truth, Aria, Emily, Hanna and Spencer feel trapped and are desperate to find a way out of this mess. With nothing else to lose, could the PLLs lose everything by putting their faith in a possibly untrustworthy ally? Meanwhile, Alison begins to build up her own army now that the PLLs have turned their back on her.

Christmas is quickly approaching, and all of Rosewood is full of merriment, except for Aria, Emily, Hanna and Spencer, who aren't feeling much holiday cheer after the loss of Mona and Spencer's cuddle charge looming over them. But when an opportunity presents itself with the chance to get evidence to clear Spencer's name, the girls and their partners devise a plan to get justice for Mona and finally bring Alison down. If the plan is successful, it could be a very Merry Christmas after all. Meanwhile, Alison gets a glimpse at the past, present and future by a ghostly presence.

Three months have passed, and Mona's friends and family are still mourning their loss and more adamant than ever that Alison had something to do with Mona's passing. Ready to put "A's" game to an end and get justice for Mona, the PLLs ramp up their search for evidence that could prove Alisonhuged Mona. But with Alison claiming her innocence and having a seemingly airtight alibi, the Liars may have to resort to more shady tactics to put Ali away.

Toby's new position in the Rosewood police department was to give the PLLs an upper hand on finally closing the door to Ali/"A's" game. But when a surprising bit of evidence show's up, Toby is put in a difficult position with his job and with Spencer. Not one to trust the police or evidence "surprisingly" showing up, Spencer tries to convince Toby to stray from his moral gut reaction, which puts stress on their relationship.

Secrets are hard to keep, especially when you are keeping them from a loved one. Spencer searches for Mona's missing laptop with Caleb's help but where the search leads them could cross the "Toby approved" line. Aria tries to get up the courage to come clean to Ezra about her lie when she gets diverted by a possible goose chase. And Hanna is stuck in the middle having to cover Ashley's secret when Pastor Ted returns with big news.

Suspecting that Alison/"A" is out to frame her for Mona's cuddle, Hanna is not willing to just sit by and let it happen. When Caleb and her friends try to come up with a safe plan to get Hanna off the hook, it isn't good enough for her. Taking her fate into her own hands, Hanna strikes out alone to clear her name.

Meanwhile, relationships are tested when Aria comes clean to Ezra and Spencer's shady actions continue to put Toby in a bind at work.

Aria, Emily, Hanna and Spencer have been burned before by newcomers to Rosewood, so it's no surprise the four ladies are wary when someone new crosses their path. Spencer lets down her guard a bit as she spends more time with Jonny, and Emily continues to try and figure out Talia as she keeps getting mixed signals from her co-workers. When Mona's friend Lesli shows up in town, Hanna is tasked to get her back story and find out if Lesli is really who she says she is. Are the girls wise to keep an eye on everyone, or can they allow a bit of comfort room without worrying it is an "A" trap?

Aria hopes Andrew can be her tutor; Spencer helps Jonny with a new project.

Determined to get college tuition money without the help of others, Hanna pushes forward with her quest to win the local beauty pageant and hires a pageant coach to ensure her win. Quickly learning that you have to be more than a pretty face to win the grand prize, Hanna turns to Emily for help. Also needing a little help, Aria asks Andrew to help keep tabs on Mike, whose increasingly suspicious behavior suggests a chilling connection to Mona's passing. What Aria ultimately discovers makes her blood run cold.

Meanwhile, Spencer decides to help Jonny on a less than legal adventure.

The Liars attempt to protect Mike and also get Alison released from prison.

A plea bargain is offered to Alison on the condition that she names one of the Liars as her accomplice.

Spencer, Aria, Emily and Caleb attempt to find some information that will clear Hanna.

The prosecution calls a surprise witness in Alison's trial; the girls hunt for last-minute evidence.

Some shocking secrets are revealed for the Liars as the biggest clue to the "A" mystery is revealed.