The students show up to class only to discover that they have been invited to a cocktail party at the Professor's house. Their invitations contain secrets— ones that they are not allowed to share with anyone else. Of course, the Party Twins and Alvaro alliance immediately breaks the rules. Once at the house, the Liars Club discovers that their task is to return that secret to its rightful owner, forever binding them together. When Bella and Benedict's cheating is revealed, however, more secrets spill forth.

While Moynihan expresses his confidence in Cuff to a local journalist, Cat's is badly shaken. She discovers Allie and Harper confiding in each other about the Liars' Club case and feels betrayed by her only friend. Left vulnerable and even more alone, Cat becomes the prime suspect when a video of her actions the night of fire is emailed to every student on campus