On this episode of Supernatural…
Castiel discovers that angels are being called but then slaughtered.
Metatron captures Castiel and tries to convince him to lead the angels against him so he can wipe them out. He also tells him that the stolen grace is going to burn him out but he can help if he agrees to a deal with Metatron.
Sam and Dean capture Gadreel. Dean almost kills Gadreel.
The brothers trade Gadreel for Castiel, but Metatron shows how powerful he is.
Castiel decides to call his flock.
Sam is worried about Dean.
Metatron claims to know the ending to the story.