At last, Julien squares off with her ex-ally Gossip Girl one final time to expose her identity. First, she convinces her friends that they need to hack Gossip Girl's Instagram account and force her to expose herself. But after Obie tips her off on the plan, Gossip Girl, aka Kate, reroutes the account back to Julien's info to hide her tracks.
After Julien finds out Obie betrayed the group, she comes up with another grand ploy, behind his back, to have Zoya claim she's Gossip Girl on the Met Gala red carpet and steal all the glory — which Kate can't ignore when she finds out about the movie rights deal. In the end, Julien, with Zoya's help, lures Gossip Girl/Kate out of the shadows with the fake meeting and gets The Spectator to report her real identity.
While Julien is victorious in unmasking Gossip Girl, she loses a friend in Luna when she unknowingly sabotages the latter's chance at a modelling campaign. During the Met Gala, the pair are approached by a rep from a modelling agency, but Julien tells them that Luna is "just my stylist, not a model." Offended by Julien's actions, Luna tells her that she's "f*cking done" and storms off. This is the last time we see the two together until the end of the episode, when Julien — joined by Zoya, Obie, Audrey, and Aki on her holiday to Rome — leads the group to a huge billboard of Luna's fashion campaign hanging up in the middle of the city. But that's not the last twist of the finale.
The episode ends on a mysterious note when Julien goes to visit an aunt of hers to inquire about her mother. Her questions go unanswered; it's assumed that "Gossip Girl" season three would've delved into that.