Dean returns from Purgatory, one year after the fight with the Leviathans. After reuniting with Sam, they find out that Kevin escaped Crowley with another Word of God that may hold the key to closing the gates of Hell forever.
Castiel decides to become a hunter, like Sam and Dean. But his first day on the job is a doozy when they investigate a series of murders caused by old cartoon gags. Meanwhile, Sam thinks back to his first time meeting Amelia's father.