Eddie's friend Charlie Pike convinces him to run away from home. Herman encourages the boy, using child psychology as seen on 'Leave it to Beaver'. Lily is outraged and sends Herman out to look for Eddie, but Herman finds a bear cub that escaped from the local circus instead.
The Munsters are off for a picnic at Paradise Cove. While out scuba diving, Herman is caught in the net of Russian Troller #47. The Russians very excitedly think they've caught a missing link between man and fish. Moscow, however, is convinced Herman is a new kind of American spy.
Eddie has entered his dad in a local rodeo bronco-riding contest. The organizers, impressed by Eddie's bragging, decide to let Herman ride their wildest horse, Volcano. Scared and nervous, Herman asks Grandpa for help, who decides to turn himself into a horse so Herman at least knows whom he'll be riding.
Herman has taken up photography as a new hobby and inadvertently snaps a picture of two bank robbers leaving the scene of the crime. The robbers in question soon locate the Munster's house (by searching for the Munster's Koach) in order to get their hands on the incriminating evidence.
Eddie is distressed after his classmates nickname him 'Leadfoot'. Herman decides to coach his boy to enter the big spring track meet, but the rest of the family is not very impressed with Herman's training methods. So, Grandpa cooks up some special 'a-go-go' pills for Eddie.
Herman and Lily's 100th wedding anniversary is fast approaching. Thinking the other has completely forgotten about it, both of them withdraw $1,000 from their bank account, and both checks bounce. Still wanting to surprise the other with an amazing gift, Herman and Lily individually acquire part time jobs at the Cleaver Employment Agency. Working as welders at the Crosby Shipyards, but not recognizing each other on account of the heavy welder's masks, Herman and Lily start flirting with each other. Tensions rise as the couple simultaneously discover each others '...
Against Herman's wishes, Lily has decided to rent the spare room. Out of 27 applicants, only one man is willing to cross the front door: Chester Skinner, only he refuses to explain his profession. Herman immediately gets jealous and, after finding a gun in Chester's room, is convinced their guest is on the wrong side of the law and must be stopped.
Herman develops amnesia after a three hundred pound safe falls on his head (and bounces off). The police take him into protective custody and rename him 'John Doe'. The only way for Lily to bring her husband home is to legally adopt him. When 'John' still doesn't show any sign of recognition after ten days, Lily and Grandpa comes up with a plan to shock John back into Herman by having Grandpa disguise himself as Rock Hudson and pretend to woo Lily. He ends up looking more like Rudolph Valentino instead.
Since none of Marylin's suitors ever get past the front door, Grandpa decides to turn a frog into her own personal prince. A nearsighted one at that, to compensate for her 'plain looks'. When the rest of the family is out to the drive-in, Marylin accidentally locks herself in her room. A young man passing by mistakingly thinks she is being held prisoner. The rest of the family assume the young man is the frog, turned into a prince, and promptly tie him up in the basement while getting Marylin's black wedding gown ready.
Herman records his own version of 'Dry Bones' as a lark on a tape recorder belonging to one of Eddie's friends. Before he knows it, the song, now known as 'That's how Herman was born' is number three in the top forty for two consecutive weeks. Lily starts to worry that Herman's ego is expanding uncontrollably.
Munster pet Spot runs away from home after Herman scolds it for leaving mud prints all over the kitchen. When Spot is sighted in the sewer system Herman goes down to fetch him, but gets lost himself. Soon local newspaper men have branded Spot a giant lizard monster, and Herman its 'mate'. The mayor, who is facing reelection, decides to bomb the sewers in order to get rid of the creatures once and for all.
Herman and Grandpa stumble upon a secret compartment through the dungeon and find a clue that leads them to Henry Morgan's pirate treasure. Lily and Marilyn are touched to see the two men working together, but as soon as the treasure is found, their companionship turns to suspicion and rivalry.
Eddie is being bullied at school by Jack McGinty, and Herman is continuously being tricked by practical joker Clyde Thornton at work. Herman advises his son to turn the other cheek, but when both come home with a blackened eye, they decide it's time to retaliate when provoked.
Grandpa claims to be working on a machine that will bring about world peace. When Herman sneaks into the laboratory at night and starts to play with it, he gets hit in the head with a bolt of lighting, resulting in a terrible disfigurement: he now looks like a regular human being. Lily takes Herman to Dr. Dudley to ask if anything is to be done with plastic surgery. Grandpa, who seems completely to have forgotten about world peace, gets out Herman's original blue prints (a gift from Dr. Frankenstein) to see if he can put his son-in-law back together the way he was ...
Grandpa discovers that the emerald ring Marilyn is wearing is the cursed Fregosi Emerald. He also discovers the curse can only be removed by a living member of the Fregosi family, the last of which lives in Detroit and runs Fregosi Motors.
Dr Victor Frankenstein IV visits the United States and brings along Johann, one of his great-grandfather's earlier, less civilized creations. Herman reluctantly agrees to take Johann home to teach him some manners with the help of Grandpa. Unfortunately, Lily mistakes Johann for her husband and takes him to the Happy Valley Lodge for the weekend.
When Eddie asks his parents for a baby brother, Grandpa decides to build a mechanical one, 'Boris' in the basement. Eddie soon begins to think that his new playmate is better loved by the family than he is, and runs away in his pajamas.
Herman and Grandpa begin to feud after the birthday present they built for Eddie is destroyed, so they split the house down the middle with a white line and agree to stay on opposite sides of it. It's up to Lily and Marilyn to get them to work out their differences so they can build a new present for Eddie before it's too late.
Herman comes home with a violent case of the hiccups after a visit to the drive-in. Grandpa attempts to cure his son in law by putting him under a hypnotic spell. That night, two freshmen from the Alpha Cappa Sorority House enter the Munsters' home on a dare, thinking it to be abandoned. Mistaking the frozen Herman for an elaborate dummy, they sneak him out of the house. Herman awakes from his trance in a girl's closet at the sorority house.
On his way back from the store, Herman is struck by an automobile. The driver of the vehicle thinks she has scarred Herman for life and offers him a cash settlement by mail in the hopes he won't sue her for everything she has got. Herman and the family get confused when they get the offer and think that they owe the woman 10,000 dollars. When the woman offers to double her cash settlement offer, Herman thinks he owes even more and abandons the family and starts to take part-time jobs all over to support himself. When Lily learns the true nature of the cash settlement ...
Eddie writes a school paper about his parents and life around the Munster home. His teacher and principal think what he has written is the product of an overactive imagination, until they head over to the Munster house and see for themselves. Grandpa invents a machine that harbors electricity from lighting bolts.