Martin's sister invites him to her very private wedding asking him not to tell their parents. Martin can't seem to keep his mouth shut and the parents not only invite themselves but they mean to have the wedding their way.
Martins sister Susan calls up to announce she's eloping and she wants him (and only him) at the wedding. Martin spills the beans to his curmudgeonly, gay father, who somehow gets the word around town to his mom. Eventually they get all their friends and family to attend, much to Susans dismay.—T