Michael retakes control of Dean as his army of monsters continue to move in; Sam devises a plan to reach Dean and stop Michael before anyone else dies.
Dean spends some bonding time with Mary and Donna. Nick finally finds the answer he has been searching for. Sam is left to make an unimaginable choice.
To distract themselves from Dean's dire plan, the Winchesters take a case involving dead bodies with mysterious symbols carved in them. Nick's past unveils a shocking desire.
Sam and Dean look to occult lore for a solution to their latest problem, but instead of a resolution, they find much more than either of them had anticipated.
Sam and Dean enlist the help of Rowena to track down a demi-god who feasts on human flesh; the challenge of keeping Michael at bay is proving to be more difficult than originally anticipated.
Sam and Castiel follow a case to a picturesque little town in Arkansas, only to find out nothing is as idyllic as it appears to be. Dean and Jack take a road trip to visit an old friend.
Sam and Dean race to help a friend in need. Meanwhile, Mary is concerned for Jack's wellbeing, and Castiel enlists help from Jo/Anael to track down a miracle.
Sam, Dean and Castiel are thrown into an epic battle. Meanwhile, Jack becomes disenchanted with all the lies, and an old friend from the past shows up.
Picking up where we left off last season, Sam, Dean and Castiel are left to defend the world after all the souls in hell have been released and are back on Earth and free to kill again.