The plan involves public exposure at a high-profile event, but Bart’s influence proves difficult to dismantle. The tension culminates in a rooftop confrontation at the Empire Hotel, leading to one of the most dramatic and controversial moments in the series' history. Key Plot Points
In the episode's climax, Chuck and Bart face off on the roof of the Empire Hotel. During a physical struggle, Bart falls over the edge and hangs on for his life. Chuck and a frantic Blair watch as Bart eventually loses his grip and falls to his death.
Fearing they will be implicated in the death, Blair and Chuck flee the scene, setting the stage for their impromptu wedding and the big reveal in the series finale. Why It Matters