For Lisa's birthday gift, Oliver plans to gets her a horse. Mr Haney delivers one, and it's not your average nag. Its name is Mr. Fred, a talking horse who's also a has-been TV star. Meanwhile, the locals decide that Lisa has a drinking habit and attempt an intervention.
It's Lisa's idea for her and Oliver to take separate vacations since they're getting on each other's nerves, but she misses him before she's out of the airport. Oliver's nerves are wrecked by her constant phone calls and the loony locals who think he kicked her out of the house. Fed up, he catches a plane to meet her; his layover in Cuba isn't planned.
Criminals rob a jewelry store in Chicago and stash their haul in a grain bin. The expensive gems end up packed in boxes of Crickly Wickly cereal shipped to Hooterville. Lisa knows real jewels when she sees them, but Oliver's sure they're just costume. After taking them to be appraised, the sheriff arrests Oliver for the jewelry store heist.
Recent law school graduate Brian Williams pitches Oliver on joining him in a new practice. After another of his patriotic speeches, this time about law, Oliver is ready to hang out his shingle. Lisa is excited about becoming their secretary, against Oliver's better judgment, and Eb is ready to take over running the farm.
The law office of Douglas and Williams is open for business, even though the sign has Oliver Mendell Douglas (later Oliver Wendell Wilkie Holmes) listed as a partner. Unqualified secretary Lisa destroys a office typewriter before having the new phone connected to a fire alarm "clanger." Later, to boost business, she advertises a grand opening special with free prizes and discount law services.
The Hooterville Young People's Agricultural Society, comprised of Eb, Hank and Arnold, flies to Washington, D.C. for the national convention. When the stewardess tries to throw the pig off the DC-3, the Douglases come on board to smooth over the problem. While Oliver tries to get the hiding Arnold out of "the occupied," the plane takes off with five Hootervillians aboard.
With the Douglases in Washington, the "Haney Farm Mindin' Service" leases out their house (for $4 a day) to a couple with six children. Meanwhile in D.C., Lisa and Eb go to the White House to have unannounced lunch with the president, Kimball causes chaos for the Secretary of Agriculture, and Arnold causes problems in a laundromat. Oliver calls an early end to their trip, forcing Haney to quickly evict the tenants who were secretly leasing the Douglas farmhouse.
After a friendly doe wanders onto the farm, Lisa starts a drive to ban deer hunting. When the governor arrives in Hooterville for the start of hunting season, Lisa presents him with her petition. He threatens Oliver and Lisa with jail time because her petition promises everyone who signed it a one-hundred dollar payment.
A check of their their marriage license reveals that Oliver and Lisa aren't husband and wife. They'd been mistakenly given a license to practice dentistry. Refusing to stay in the house with a bachelor dentist, "Dr. Gronyitz" moves in with the Monroe brothers until they can re-tie the knot. Their church wedding suffers on minor distractions considering Hank Kimball is the best man and Ralph Monroe is the maid of honor.
While all of Hooterville is excited about the upcoming big dance, Eb is obsessed with raising $20. He wants to buy his girlfriend a birthday present and take her to the "swanky" Pixley Diner (which has tablecloths). Oliver refuses to advance him the money, telling him to be ingenious. First, Eb begins leasing out the Douglas' wardrobe and telling folks that the couple's strapped for cash. After Oliver puts a stop to that foolishness, he babysits ten babies at once while their parents go to the dance.
From inside an old trunk Eb found in the barn, Lisa begins reading the diary of Lydia Plunkett who, in 1898, becomes a traveling saleswoman for a corset company. Lydia falls in love with rival salesman Harry Wright, whose career falters as a result of her success. The two marry, she becomes president of the corset company, and unhappily tends house. He eventually tires of being a housewife and leaves her. As Lisa continues reading, Eb is entranced by the story, but Oliver scoffs at the soppy romance.
Local inventor "Looney Luke" Needlinger has built a contraption that turns hay into milk. Convinced it will make them rich, Haney and Fred pitch Oliver on investing in the machine, but he thinks they're being conned. After seeing the milk maker in action, Oliver convinces a chemist to give the device a once-over. What he discovers insures that cows will always have work.
Oliver, Lisa and Eb talk about reincarnation after watching a movie about a grandfather who returns as a racehorse. Later, when Eb goes missing during a nasty thunderstorm, Lisa is worried sick that something bad has happened to him. She's greatly relieved when he returns home safely--"re-incarcerated" as a dog.
Lisa's mother surprises her and "Whatshisname" (Oliver) with a three week visit. She just became a countess--the title came with an estate she bought--but Eb tells everyone she's the Queen of Sicily. In her royal honor, the locals hold a Ceremonial Day and present her with a solid gold wooden key to the city. The highlight is a 21-gun-salute using just one cannon and three balls.
Two weeks of boredom is finally enough for Lisa's mother. To Oliver's relief, the woman who still doesn't know his name is packed and ready to go. His celebration is brief once greedy Mr. Haney and Joe Carson learn she's filthy rich. The pair of money-hungry Romeos descend on the Douglas house to vie for her attention (and fortune) before being tossed out for fighting.
The descendant of Herman, a pig that predicted the weather with his tail, stands to inherit the $20,000,000 Birnbacher estate. Fred Ziffel is convinced it's Arnold who has possesses same talent. Everyone in Hooterville pressures Oliver to take Arnold to Chicago and claim his inheritance. Oliver, however, isn't interested in accepting the embarrassing job of professional "pig lawyer."
"Famous pig lawyer" Oliver Douglas arrives in Chicago with Lisa and Eb to prove Arnold's the rightful heir to a $20,000,000 Birnbach pork fortune. While Arnold is given the royal treatment by the hotel staff, the Douglases are brushed aside as persona non grata and shoved into a room the size of a closet. At the lawyers' meeting to claim the money, Arnold's tail makes the ridiculous prediction of snow in July. The red carpet is suddenly rolled up and they're all given the bum's rush out of the hotel.
When the Douglases, Eb, and potentially wealthy Arnold return from Chicago, the pig goes on a gift-giving spree. Mr. Kimball gets a wristwatch, Lisa, an expensive bracelet, and Oliver, a shrunken head. With Arnold the target of every salesman in the valley, he hides out at the Douglas farm. Soon they've tracked him down and it's Oliver who has to fight off the pushy peddlers. Before being pulled off the telephone pole by a salesman, Oliver takes a call from Birnbacher's lawyer informing him the will is being contested by the late eccentric's sister-in-law.
Oliver's steamed over Hooterville's dirt road, especially after learning the money to pave it was appropriated thirty years earlier. Never content to leave well enough alone, he descends on the state capitol demanding that something be done. The state finally agrees to start the project, but will have to tear down the Ziffel's house in the process. Oliver makes no headway on saving their home until Lisa drops the name of Mr. Haney's cousin, powerful hot dog vendor "Big Joe" Haney. Thinking all problems are solved, Oliver is shocked to hear the locals are planning to ...
Lisa the fortune-teller predicts that a mysterious stranger will soon enter Oliver's life. That stranger is Tadpole Talbot, Eb's childhood buddy who's now a singing sensation. Tadpole hires Eb to go on the road with him and plug his music, but it's not nearly as glamorous he'd imagined. Eb's brief music music career ends in an explosion when he plugs Tadpole's AC guitar into a DC outlet. Lisa sends her "son" money so he can come back home.
Alarmed by the dropping population of Hooterville, Oliver calls a town meeting to find ways to keep the young people from moving away. Lisa urges him not to become involved because his "goo dooding" always backfires, but he forges ahead anyway. Soon, he's involuntarily volunteered his barn to be the valley's new youth center.
Oliver tries to pick up a special delivery letter that arrived for him at the Hooterville post office. He and Lisa end up traveling all over the valley because Postmaster Drucker mistakenly gave it to Hank Kimball, who gave it to Fred Ziffel, who gave it to his son Arnold. Arnold dropped it in the mail, sending the Douglases to the Pixley post office where two sets of identical twins are working at the windows.
Oliver speaks about a law career at Hooterville High and makes a great impression on one student, Cathy, a teenage girl who develops a crush on every speaker who visits. Lisa's irritated when the smitten girl starts showing up at their house fawning over her "groovy" husband and calling her old. Oliver also has to contend with her jilted boyfriend who's angry that he broke them up.
While under the influence of medication, county agent Hank Kimball proposes to lady carpenter, Ralph Monroe. The two go through the wedding ceremony, only to find out that Justice of the Peace Sam Drucker's license has expired and they aren't really married.
With minimal help from Eb, a stressed Oliver begins planting his corn crop. Lisa tries to be a useful farm wife, serving dreadful lemonade which Oliver pours out dumps out in the field. The next morning at that spot, he finds a giant cornstalk that reaches up into the clouds. At the top of the stalk there's a Jolly Green Giant who bellows "Ho, Ho, Ho" and drops down creamed corn, both in the can and by the bucketful.
Sam Drucker stocks hardly any "cosmeteticals" in his store, so Lisa offers to put together a display for his business. When 395 cartons of Lady Love cosmetics are delivered, she forces Drucker out onto his front porch and turns the who building into a "beauty saloon." Oliver tells her she must move her business somewhere else, so she sets up shop in their living room, tossing all of their furniture into the front yard.