The apocalypse is coming, and Sam (Jared Padalecki) and Dean (Jensen Ackles) prepare for the fight in very different ways. Sam joins Ruby (Genevieve Cortese) on a final run to kill Lilith (guest star Katherine Boecher), while Castiel (Misha Collins) and Zachariah (guest star Kurt Fuller) tell Dean it's time to play his part in stopping Lucifer.