Looking to reclaim his place as King of Hell, Crowley asks Dean for help finding "The First Blade," the only blade that can kill Abbadon. Knowing he owes Crowley a favor for helping Sam, and also wanting Abaddon dead himself, Dean reluctantly agrees and the two set off on a road trip. However, Dean and Crowley are completely unprepared when they find out who has the blade - Cain, the first son. Meanwhile, Sam is back at the bunker with Castiel who notices there is some leftover grace inside Sam. If they can extract it, they can use the grace to track Gadreel. The only problem is the procedure may do permanent damage to Sam.