San and Dean go looking on the black market for the blood of “a most holy man”, and become involved trying to recover the stolen skull of St. Peter.
Donatello translates the spell and Dean and Castiel go to get the ingredients. Meanwhile, Mary and Jack escape Michael’s captivity and meet an old friend for the first time.
After Castiel makes his way back to Sam and Dean, they set out to find Lucifer and gain an unexpected ally. Meanwhile, Lucifer finds a cooperative angel and makes Heaven’s angels an offer that they can’t refuse.
Two young witches use a love spell to get what they want… and they want the Black Grimoire stored at the bunker. Meanwhile, Lucifer and Castiel try to escape from Asmodeus’ imprisonment, and are forced to work together.
Donna’s niece Wendy goes missing near a truck stop, and she calls on the Winchesters for help. They soon discover that Wendy’s abductor is part of an online business providing food to monsters.