Derek and Richard finish Burke's surgery as Denny successfully undergoes his heart transplant. Until one of them admits to cutting Denny's LVAD, the interns must attend to Richard's niece, which includes giving her a prom. As they each struggle with their own personal problems, they blow up balloons, hire catering, and decorate. As everyone works around him, Burke unfortunately finds a tremor in the movements of his right hand. Meredith and Derek sadly make the decision to put Doc to sleep. Richard continues to interrogate the interns, one by one, not receiving any direct answer about Denny's LVAD wire, only learning his interns' personal problems themselves. Izzie accepts Denny's marriage proposal. Meredith, Derek, Addison, and Finn finally put Doc to sleep as the hospital staff begins to arrive, dressed in full prom regalia.

As everyone dances and mingles, Meredith and Derek escape Finn and Addison to have a heated argument that only turns into a long awaited reunion. Meanwhile, alone in his room as Denny waits for Izzie, he experiences a sudden sense of pain, and he slowly closes his eyes... dying from an unexpected blood clot. Izzie runs to Denny's room to find only a code team, desperately hurrying in the same direction. One by one, the interns hurry to Denny's room to find a shocked Izzie, lying in bed next to his still form. As they each comfort her in any way they can, they all leave together and listen as Izzie confesses to Richard that she cut the LVAD wires. They only look on as they continue to listen to Izzie quit the program. After everyone begins going their separate ways, Meredith remains torn on who she should follow... Derek or Finn.