With Emily pushed to her limits, the girls finally confide in Dr. Sullivan about "A." Meanwhile, Hanna's grandmother (Betty Buckley) arrives in Rosewood as Tom's wedding nears.

The Halloween before Alison vanished finds her facing a possible usurper to her queen-bee throne. Meanwhile, Aria uncovers something surprising about her dad; and Spencer struggles with her class-election campaign as she deals with parental disapproval.