Before the Flood (S04E22)

Sydney, Jack, Irina (Lena Olin), Vaughn and Nadia are the last hope to save the world from the catastrophic effects of the Rambaldi end game – put into action by Elena Derevko (Sonia Braga). Meanwhile, the Rambaldi prophecy surrounding Sydney and Nadia comes one step closer to becoming reality, Sloane's true allegiances are realized, and Vaughn asks Sydney a momentous question. (iTunes)