Dean & Bobby are waiting for Sam to wake up. Apparently he hadn't woken up and they were worried. But same does wake up and he doesn't remember anything. The last thing he remembers is being Lucifer's meat suit and falling in the cage. So Dean just tells him that he's been gone for 1.5 years and leaves it at that. Of course Sam has questions for him. Bobby is nervous around Sam because he tried killing him so he won't really talk to him. Dean & Bobby are going on a hunting job and Sam wants to go so Bobby hangs back. Turns out something is kidnapping virgin girls. They figure out that it is a Dragon once one of the girls doesn't get taken because she was wearing a purity ring but really wasn't a virgin. So that's how they get a description. Dean calls Bobby and he sends him to a woman to find out how to kill the Dragon. While Dean is gone, Sam calls on Castiel and kind of tricks him into telling him everything. So now Sam knows. Dean finds the woman and turns out she has a romantic past with Bobby. She tells him that to kill a dragon you need a special blade forged from dragon's blood. She happens to have one in her basement stuck in a rock like Excalibur. Dean of course tries to pull it out with dramatic music and all but he can't do it. So he decides to blow up the rock and in the process part of the blade. So now they know they have to get pretty close to the dragon. Sam has figured out that the dragon is in a sewer tunnel and that's where they head. They find a bunch of girls, fight several dragons, kill a couple of them and one gets away. The girls are saved.
Bobby finds a book about dragon lore and virgins and they are used to open a portal into Purgatory and summons something. So now we meet the new villain, Mother, which had been mentioned by the Alpha Vampire a while ago.