Marilyn’s boyfriend, Tom Daily, invites the Munster clan to a masquerade. Eddie remains at home with Mrs. Morton as his sitter. Marilyn goes as Priscilla, Lily is Little Bo Peep, Grandpa is Napoleon and Herman is King Arthur in a suit of shining armor.

Herman has a twin brother Charlie who is a con-artist. He comes to town and ends up stays at the Munster home, which doesn’t make Herman too happy. Charlie claims to have made an invention that takes uranium from seawater, he’s looking for an investor. Herman thinks that the whole thing is a scheme to get a Lily’s $5000 inheritance, he ends up being right.

Grandpa is feeling lonely and depressed so he contacts a matrimonial agency to find a mate. The agency sends over a nice looking elderly woman who find Grandpa to be delightful. She turns out to be the Black Widow: she makes her living by marrying her suitors, getting them to sign a life insurance policy naming her as beneficiary, and then murdering them.

The Munsters have been chosen by Event Magazine as the average American family. Grandpa is insulted by being labelled ""average."" He disappears, jeopardising the family's photo opportunity and the large amount of prize money that came with it. When a journalist and photographer arrive at the Munster home, Herman and Lily think they are burglars.

The Munsters have been chosen by Event Magazine as the average American family. Grandpa is insulted by being labeled “average”. He disappears, jeopardizing the family’s photo opportunity and the large amount of prize money that came with it. When a journalist and photographer arrive at the Munster home, Herman and Lily think they are burglars.