Based on the long-running CBS TV sitcom, The Beverly Hillbillies, a poor hillbilly named Jed Clampett (played by Jim Varney) goes hunting on his land one day and becomes a billionaire when he misses an animal with his rifle and the bullet hits the ground, sending up a bubbling geyser of crude oil.
Diedrich Bader later made a reference to his role in the film in an episode of The Drew Carey Show.
Part of the country-meets-city humor comes when the hillbillies reach Los Angeles and an angry driver flips Jed the finger. The hillbillies all mistakenly think that is the "Californy howdy," so they start making the obscene hand gesture to other motorists. When they give the finger to one particular couple on the highway, the passenger pulls his gun on them. Jed thinks the man is just showing off his firearm, so he shows the man his shotgun. This scares them away.
Once they arrive in Beverly Hills and locate their mansion, which has been provided for them by the banker in charge of Jed's billion dollars, Milburn Drysdale (played by Dabney Coleman), which he purchased next door to his own with the help of his secretary/assistant, Miss Jane Hathaway (played by Lily Tomlin), the Clampetts are perceived to be transient derelicts and the police are called. Miss Jane gets there and discovers their true identity as Mr. Drysdale arrives. The fawning and covetous Drysdale convinces them that all is well. In fact, Jed tells Miss Hathaway, "I reckin' you done what you done cuz ya didn't knows we was who we was. If we hadn'ta been who we was, we'dda been plentya grateful for youa doin what ya done."
When they get settled into these large and strange surroundings, the country folk are very naive with regard to life in the big city and have to contend with a serious culture clash, strange and unusual customs, and snobbish neighbors, especially Mrs. Drysdale (played by Penny Fuller).
Wanting to make Elly May into a "sophisticated woman," Jed decides she needs a French tutor to help her acquire more ladylike ways. He then expresses a desire for a new wife, for Elly's sake. The Clampett clan, along with everyone else, set out to hunt him down a bride. Since he is filthy rich, there are plenty of women who will gladly marry the plainspoken former coon-hunting billionaire and become Mrs. Jed Clampett. Woodrow Tyler (played by Rob Schneider), an employee in Drysdale's bank, contrives a scheme to bilk the bumpkin hillbilly out of his billions. He gets his golddigging, con artist girlfriend, Laura Jackson (played by Lea Thompson), to go to the front door of the Clampett mansion posing as a French etiquette teacher, Laurette Voleur (voleur means thief in French), asking for work.
Once she is hired, Voleur lures Jed into proposing marriage and plans are set. All the Clampett's kin from back in the hills, including Pearl and Jethro's twin sister, Jethrene Bodine (also played by Diedrich Bader), fly to California for the wedding. Granny, however, hears Laurette Voleur and Woodrow Tyler talking about their scheme while she is brewing some moonshine, and she jumps up and yells, "When I inform Jed, the wedding will be off! Hehehe!" They grab her and then tie her up and gag her and take her to the Los Viejos Nursing Home and put her there against her will where they tell the head doctor she is their grandmother who suffers from dementia. Voleur demands she be kept restrained in a straitjacket at all times because she is a danger to herself and others and that she is to be kept away from sharp objects and pay phones. The doctor says she will be a fine test patient for electro shock therapy and should be tested for rabies.
Miss Jane, searching for a private investigator to locate Granny, goes to the offices of Barnaby Jones (Buddy Ebsen, who portrayed the original Jed Clampett in the TV series, recreating the title role of his later TV series).
During the big, elaborate wedding, Woodrow plans to transfer all of Clampett's money in Drysdale's bank to a Swiss account on his laptop computer when the couple says "I do."
However, the plot is foiled when Miss Jane finds out from Barnaby Jones that Granny is in the retirement home. Miss Jane dresses up like the new nurse and breaks in and tells the orderly that she is here for the rabies test. The orderly tells her to be careful, they had to give her electro shock therapy. She gets to Granny's room and finds her restrained in the straitjacket with her hair frizzed up from the electro shock therapy. Miss Jane unstraps her from the restraint and helps her escape from the doctor and the home. They arrive at the wedding in time to foil the plot. The Clampetts learn that "sparking" and marrying are not the same in Beverly Hills as back home in Bugtussle.
The end credits are shown over various outtakes and bloopers.
In the scene showing the White House (as the residence of cousin Bill), the flag on top is at half mast.