With all signs pointing to Lesli as the tormentor in the hoodie, the PLLs are on a mission to get concrete proof before bringing their findings to the police. But as the girls ramp up their investigation, "A’s" threats escalate.

Meanwhile, a friend of Emily’s makes her a surprising offer, and Spencer is pressured by her family to make an important decision.

After their latest run-in with Charles, tensions are at an all-time high with the PLLs and the town of Rosewood. Aria’s big moment of seeing her work displayed in an art gallery is in jeopardy as Ella is determined to keep her safe at home. Hanna is still uncomfortable with the unexpected scholarship money and is determined to give it back, even if that means ruining her chances at going to her school of choice. And to top it off, the one normal high-school rite of passage the girls are looking forward to is in danger as Rosewood High is considering not letting the PLLs attend prom due to security issues.

Meanwhile, the more Alison learns about her brother the harder she finds it to connect a deranged murderer to the young blonde haired boy she sees in the photos and in her memories.

As the girls are forced to stay in Rosewood, questions about the new mystery surface. A restless Aria starts to look suspicious as she heads back to Boston a little too quickly. But could Aria really be the one behind this? As Spencer, Emily and Hanna find themselves back in familiar territory, they aren't happy with going about solving this puzzle "the old way."

Meanwhile, Emily continues to lie about her life in California and Alison keeps a close eye on her friends.

After Alison is confronted with a sudden, mysterious jeopardy, the Liars decide to take things into their own hands for a counterattack. Hanna and Caleb work together to develop a plan to come face-to-face with the tormentor. Emily and Spencer team up to investigate if Mona had any involvement with the murder. Aria and Ezra continue to work on the book though it might be more difficult than anticipated.

Meanwhile, Ali encounters an unexpected visitor.

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.

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.