With Paranoid Frank filling the Bobby-shaped hole in the brothers' life and their investigations into Dick Roman turning up "dick", the Winchesters have a chance to do a good, old fashioned bit of monster hunting.
As has been a common - and welcome - thread this season Plucky Pennywhistle's Magical Menagerie draws on the show's seven-year backstory, this time Sam's coulrophobia (fear of clowns).
This episode is a perfect example of bread'n'butter Supernatural - a mystery, the brothers doing research, some monsters, some gore and all tempered with a dash of knowing black humour.
A man mauled apparently mauled to death by a giant vampire octopus draws the Winchesters to Kansas and when another is impaled by a unicorn they discover the connection between the men is Plucky Pennywhistle's Magical Menagerie, a clown-themed pizza chain for children... where Dean used to dump Sam as a kid when he went off trawling for girls.
Besides the murders, the bulk of the episode is taken up with Sam and Dean's investigations, the curtain only being pulled back to reveal what is actually going on in the final act.
This episode may not have moved the Leviathan arc forward at all, but it showed that Dean has turned a corner with his issues from earlier in the season and Sam finally got to confront his major phobia - in a knock-down, drag-out brawl with pair of indestructible, magical clowns!