Pam is distraught and spends the first 30 seconds of the episode crying until Archer snaps her out of it with relatively violent means. She confesses that she's distraught that her sister Edie is getting married and she wasn't selected as the maid of honor. To add insult to injury, Edie's groom is someone Pam used to crush on.
Out of pity, Archer agrees to be her wedding date.
Archer's nemesis Barry spots them in the airport as they're en route to Green Bay, Wisconsin and rearranges his itinerary to follow Archer. Pam and Archer arrive in Wisconsin and are greeted by Pam's sister who is more blunt than Pam (she thinks Archer is gay and a hired boyfriend and has no hesitations voicing them) and a lot more of a jerk.
Barry then shows up and Punches Pam out. He takes her hostage and calls Archer's motel room with instructions to meet Archer by the grain elevator on the other side of town if he wants to see Pam alive again.
Archer obliges but Edie doesn't buy all this secret agent stuff, so Archer solves this quick fix by punching Edie's lights out.
The big showdown goes down at the grain elevator after a spirited debate between Archer and Edie over why a grain elevator is vertical rather than horizontal.
Archer is overmatched by Barry but he remembered to lace his shotgun with explosives which does away with Barry. Barry is stripped down to his exoskeleton a la Terminator and luckily for the jealous Pam, the wedding appears to be off.
In the B-plot, Lana searches for a babysitter for AJ.