"There are two distinct episodes in this two-hour fire-and-brimstone buffet event. For the appetizer, "Let It Bleed," Dean faces his worst nightmare when Lisa and Ben are unexpectedly abducted. In the main course finale, "The Man Who Knew Too Much," the war in Heaven comes to a head. Castiel faces off with Raphael and the walls holding back Sam's memories of Hell crumble. Someone (human? angel? demon?) will die and someone will be transformed. Prepare to gasp, possibly cry and write angry forum entries. Oh, and sorry, John Winchester won't show his face for the finale."
Source: TV Guide