On this episode of Supernatural…

Castiel searches for Lucifer and teams up with Crowley to do so.

Lucifer’s vessel is deteriorating and he wants Rowena to fix it.

Rowena creates a spell to make the vessel decay faster, and Lucifer goes away.

Sam, Dean and Mary tackle a case involving ghost children.

Mary has flashbacks to the night of the yellow-eyed demon.

Mary figures out the cause of the haunting, and she helps Sam and Dean stop it.

Mary decides to leave for some time, talking about her struggles with being back.