The Munsters’ pet Spot runs away from home and is mistaken for a dangerous monster when he is sighted in the sewer. When Herman goes down the manhole to search for Spot, he too is mistaken for a dangerous monster. The Mayor vows to rid the city of these menaces by using TNT.

Dr. Victor Frankenstein IV from Germany visits Mockingbird Heights and brings with him Johann, Herman’s look-alike cousin. Johann is quite primitive and behaves like the Frankenstein monster from the movies. It is up to Herman to try to civilize him and teach him English. Lily is not informed of this; mistaking Johann for Herman, she takes him away for a romantic weekend getaway.