 Marilyn s hanging out with Tom Daly, a young man from a good family. She s very happy with him, but he hasn t met Marilyn s family. So, Tom s family sends an invitation to Herman and Lily, for a masquerade dance party. But Grandpa hasn t been invited, and Lily intercedes and calls to Mrs. Daly, asking if Grandpa can go to the party too. Surprised, Mrs. Daly says that there s no problem if that Grandpa person assists to the party. Mrs. Daly tells her husband about the matter. They re suspecting about Munsters  good manners. Herman disguises himself as King Arthur, wearing a heavy armor. Lily disguises herself as a shepherdess (quoting Herman, she looks "positively awful") and Marilyn is a pilgrim. Grandpa disguises himself as Napoleon, mixing up the potions of Marlon Brando and Charles de Gaulle. At the party, things aren t going so good, because Mr. Daly hasn t talk with Herman. Besides, Grandpa is behaving in an eccentric way with Mrs. Daly. Marilyn encourages his uncle to talk with Mr. Daly, who has disguised himself as Frankenstein monster. Herman tells him that he reminds him to someone, adding that is curious that he isn t wearing a costume in his own masquerade party. Of course, Mr. Daly will get mad with Herman. The moment of award the best costume arrives. Herman gets the prize for the best King Arthur costume, and everybody asks him to take off the helmet. One man disguised as George Washington says that Herman is the best, because he s wearing a mask over another mask. Lily gets angry, and tells Herman that they re leaving, because they have been insulted. Herman s having fun, but after seeing himself at the mirror, concludes that he s been insulted. Marilyn is angry as well with Tom s family. Tom takes Marilyn home, where he finally meets Herman and Lily, but without their costumes. Tom runs away after seeing Herman, but Marilyn feels relieved about that. She didn t like Tom s family anyway.