In the fourth-season opener, the girls team up with Mona to try to understand "A" better. Meanwhile, Aria doesn't look forward to seeing Ezra after their breakup; Emily makes plans for her future; and "A" charts a new course for Toby.

The girls are curious about Melissa's return visit to Rosewood. Meanwhile, Hanna meets with Det. Holbrook in an attempt to help her mom; a clue left by Ali leads the girls to an eerie mask maker; and Emily's mother is targeted by "A."