Meanwhile, the boys plus My Sweet Baboo have reached a very familiar-looking stairwell, and barely have they made it past the main landing on their way down to the first floor when Castiel suddenly explodes backwards in a blinding flare of golden light. Zombie Grandpa just slapped his bloody palm against an Angel B-Gon Sigil of his own design, you see, so My Sweet Baboo is now officially out of the picture, and my interest in the remainder of this episode just plummeted down to zero. "You sold us out?" Dean howls the instant he realizes what everyone in the audience has known since Zombie Grandpa's last scene. Crowley rounds a corner behind Zombie Grandpa just as his two henchdemons materialize to apprehend Our Intrepid Heroes, and Crowley basically confirms that yes, Zombie Grandpa sold out his only grandchildren so Crowley could resurrect Burnt Mary, who immolated her unearthly remains way back in the first season, so there's nothing left of her to resurrect. Dumbass. That "dumbass" was directed at Zombie Grandpa, but it could just as easily apply to any of the other gentlemen now gracing my television screen, or indeed to any of the sadists responsible for this crap on a weekly basis.
In any event, after listening to a few more sneering remarks from Crowley, the henchdemons manhandle Our Intrepid Heroes into another wing of the abandoned facility, where they fling them into otherwise empty cells.
Meanwhile, back at the Hellhounds, Meg slaughters the last of the invisible beasts, and would take a moment to compose herself, I'm sure, were it not for the fact that Corin Nemec just popped up from out of nowhere to deck her in the chops. Meg goes down like Boston's Big Dig, and Corin Nemec menaces at her for a very long moment until the camera hops back over to...
...Sam and Dean's cells, where the two commiserate over the deplorably filthy conditions for a bit until Zombie Grandpa swings by to explain himself, and because this whole Burnt Mary thing is so obnoxious and ridiculous and FUCKING STUPID for reasons I have carefully outlined above, I'll be ignoring all of it. Well, most of it: You should probably know that Dean vows to slaughter Zombie Grandpa the next time he sees him, but other than that? It's worse than the refuse now soiling Sam's boots.