The angels fell and they're angry. The brothers chose each other instead of shutting the Gates of Hell and now, Sam is in the hospital, fighting for his life. Dean, who's willing to do anything to save his brother, says yes to an ally he knows nothing about. But, healing Sam isn't Dean's only problem. Abaddon and Cashmere have returned and they're looking to take over Hell. When Faith returns to her brothers, they question whether or not she really is their sister. What will the Winchesters have to do in order to set things right?
When Allison Argent dies, a mix-up happens and her soul gets sent to the wrong place. When Castiel finds out, he does his best to right this wrong, but Allison's mind is too damaged to send her back to her family and friends. So instead, Castiel tasks the Winchester brothers with aiding Allison in her recovery.