Dean (Jensen Ackles) is devastated after Kevin's death and vows to find the angel that killed him, not only to free Sam (Jared Padalecki), but to seek revenge. Castiel (Misha Collins) arrives at the bunker and suggests they try to separate Sam's brain from the angel's so they can talk to Sam and have him expel Gadreel.   However, there's one small problem: the only person who knows how to do that is Crowley (Mark Sheppard).  Robert Singer directed the episode written by Andrew Dabb (910).