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.

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.