Darling Sammy opens the episode all dolled up in FBI drag, the better to investigate a series of brutal and bloody murders in Lansing, Michigan, at the behest of Zombie Grandpa. Something, you see, has of late been breaking into various young marrieds' homes, slaughtering the young marrieds, and absconding with the now-dead young marrieds' six-month-old children. Even though Sam attempts to convince Zombie Grandpa that This Is Not Their Sort Of Thing, Zombie Grandpa quite correctly points out that even if it isn't, there's still someone out there collecting babies, and as the Lansing police seem especially inept, Sam might as well see what he can do about it. Acting on a hunch, Sam discovers all of the murdered marrieds had alarm systems installed by Harper Caine Security and races to the home of the last couple on the list. Of course, he's too late to save the parents, but he does end up with an adorable infant as compensation for all of his troubles.

Meanwhile, Paranoid El Deano's gone into extreme lockdown mode somewhere else, moving Bendy Lisa and The Brat from Cicero after the boring events of last week and refusing to allow either of them to leave their new house. Needless to say, this state of affairs pleases neither Bendy Lisa nor her Brat, so it's with no small amount of relief that Bendy Lisa sends Dean back on the road after Sam pleads for his big brother's help with the unexpected infant. Unsurprisingly, neither Sam nor Dean takes to parenting all that well, and wacky hijinks abound until the two run into a shapeshifter who tries to swipe the unexpected infant in the middle of a grocery store, because it turns out the unexpected infant is half-shifter himself. An "alpha" shapeshifter apparently decided to increase his species' numbers by temporarily posing as various young married Michigan males, knocking up the guys' wives, and then returning fifteen months later to claim his progeny.

The boys flee with the unexpected infant to the Campbell Compound, where dicks are hauled out and measured until the alpha shifter shows up, kills the only Campbell Cousin I liked, and vanishes with the unexpected infant after displaying some mad shifting skillz by simply shimmering from form to form, rather than molting in that spectacularly disgusting way to which we've become accustomed when dealing with monsters of this particular type. Later, after the dust has settled, we overhear one half of an ominous-sounding conversation between Zombie Grandpa and the entity he's secretly working for that makes it clear he's collecting monster specimens for some bizarre reason, but we don't learn much more than that.

And in the end, Bendy Lisa releases Dean from his obligations, so Our Dear Boys are finally free to embark upon the sixth season proper. In Metallicar. Hooray!