Once again, we get an episode that picks up immediately where the last one left off, so it's back down into the blood-streaked bowels of Crowley's laboratory for us, where we find the badly battered Dean and Bobby cowering in the presence of whatever the hell it is that My Sweet Baboo became at the end of last week. Unfortunately, the tens or hundreds or thousands of Leviathans swimming around inside what's left of Castiel's gut soon start melting the Vessel, so The Leviathans beat a strategic (and incredibly drippy) retreat to the local municipal reservoir, where they dissolve themselves -- and what's left of Castiel's body -- into the water supply for Stockville, Kansas.

For whatever asinine reason, Our Intrepid Heroes -- who witnessed the entirety of Castiel's soggy end, mind you -- fail to notify the proper authorities of the inky-black foulness now poisoning the reservoir, thereby effectively granting The Leviathans liberty to possess the entirety of the town's population at their leisure, so I guess it's to the monsters' collective credit that they initially assume control of five or six people, tops, including a little girl named Annie, a demolitions expert named Edgar, and two Stockville High Sharks, the latter of whom promptly eat all the other guys on their swim team, in the process drawing national media attention to the little burg. Leviathan Edgar, who seems to be some sort of trusted deputy of the as-yet-unseen Boss Leviathan, orders Leviathan Annie to do a better job keeping things on the down-low for now, so she pouts and mopes and watches a lot of shitty TV and eventually stumbles across a masterful and cunning plan: If they assume control of a large urban hospital, they'll have access to all the human organs they could ever hope to eat, and more.

Naturally, the large urban hospital they decide to occupy is Sioux Falls General, because why pick something convenient in nearby Kansas City when you can travel two states and four hundred miles away for the same thing, right? Fortunately, Sheriff Jody Mills happens to be on one of the wards when the invasion begins, recovering from an appendectomy, so she's able to sound the alarm the minute she notices something strange -- you know, like her doctor eating her roommate's liver -- and Our Intrepid Heroes plus Bobby are soon on the case. Well, Dean and Bobby are soon on the case, because Sam's still having lengthy dialogues with the imaginary Satan who lives deep inside that freakish Cro-Magnon skull of his, but that's not the real problem. No, the real problem is that these Leviathan things are pretty much unkillable, and they're under orders to take out Sam, Dean, and Bobby as quickly as possible.

To that end, Leviathan Edgar incinerates The Emporium -- I know! -- before vanishing Bobby and laying a smackdown on Our Dear Boys that's actually -- for the first time in the history of this show -- really injurious. Yep, the monster shatters Dean's shinbone in about three different places and whacks Sam into a life-threatening concussion before Dean manages to drop a car on the thing, and the episode ends with a decidedly atypical cliffhanger that involves Sam flipping into a seizure in an ambulance that's whisking Our Intrepid Heroes straight into the mouth of the monsters' lair at Sioux Falls General, despite Dean's mighty entreaties for the paramedics to avoid the place at all costs. The whole thing left me feeling cautiously optimistic for this Leviathan storyline, so I'm sure they're gonna fuck it all up next week.