The seniors put on a production of The Age of Innocence and find their personal lives mirroring the play. Serena develops a crush on the play's director, Julian, and enlists Vanessa's knowledge of theater to help her get his attention. Blair receives devastating news about her future that leads her on a witch-hunt for the person responsible. Dan and Rachel agree to stay away from each other in the aftermath of being discovered as more than teacher and student, but find it impossible to keep that promise. Chuck enlists help from an unlikely source, his nemesis Carter Baizen.
Title comes from the 1920 novel The Age of Innocence.