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.

Grandpa mixes up a love potion designed to make the opposite sex fall madly for anyone who drinks it.

Herman is suffering from insomnia. The only thing that will make him sleep is a late-night walk in the park. A 'monster' type creature has been spotted in the park at night and Lily would prefer if Herman would stay home. What she doesn’t know is that the monster is Herman!

Herman and Grandpa overhear Lily and Marilyn talking and somehow get the idea that Lily is pregnant. What’s really happening is Dr. Dudley’s son, Elmer, is coming to stay with the Munsters while Dr. Dudley and his wife are on vacation.

Herman takes up amateur photography and accidentally snaps a picture of two men making their escape from a bank robbery. Herman has visions of getting a big reward for his evidence, but the bank robbers track him down and decide to hold up with the Munsters until the heat is off. This episode revisits the show’s recurrent fascination with criminality, especially bank robberies.