When the Levee Breaks (S04E21)

Dean and Bobby (recurring guest star Jim Beaver) lock Sam in Bobby's panic room so he can detox from the demon blood. However, as Bobby sees more seals are being broken he tells Dean they should let Sam out to help them fight the impending apocalypse. Dean disagrees and goes to Castiel (recurring guest star Misha Collins) for help. Sam and Dean have a big blowout confrontation. (Warner Bros. UK)