To capture the affections of a pretty blond, Robbie turns pop composer and produces a novelty song. The family agrees to do the vocal background, but when they are selected to sing the song on television, Steve gets a bad case of stagefright.
The Douglas family inherit a castle in Scotland from their Scottish Grandfather and the whole family descends upon Sheehan Bridge to see it. Not only does 'The Castle' turn out to be an entire village pub in the highlands, but other members of the clan give them a freetly welcome.
It's a bad day for Steve when everything seems to be going wrong for him. His run of bad luck starts when he cuts himself shaving, burns his hand on the toaster, and then can't get his car started. Worse yet, he has to clinch a deal with a very important client.
Robbie is chosen to write an 'advice to the lovelorn' column for the school newspaper, but Steve gets caught in the middle when a baffling love letter arrives. Robbie suggests that the writer should elope with her boyfriend and Steve tries to talk her out of it.
Mike offers to give Robbie his old car but his response baffles everyone. Robbie says he needs his own car to impress a new girl and does some fancy wheeling and dealing to get it.
Steve gives Mike advice on love after he announces his passion for his new girlfriend Darlene, who Mike wants to devote time to, so he hardly welcomes Steve's suggestion that he help find a date for the girl in his office.
Chip and his new sidekick Ernie find some old treasure maps but get lost in the woods when they go treasure hunting, causing the family's plans to be changed when they have to go looking for them.
Chip and Ernie, having heard two scientists calculate that the world will be destroyed in one week are faced with the classic problem of what to do in the time they have left.
The pungent smell around the Douglas home proves to emeante from Bub's head for his baldness is anointed with yet another hair restorer as he's in a panic to cover his bald spot when the sister of an old buddy comes to visit.
Robbie is faced with a real political dilemma when he and a rival for a girl's affections, are campaigning for Student Council Representative.
Mike gets cold feet when he decides to propose marriage to Sally. His bungling attempts further confuse the issue. He tries a combination of methods derived from the attempts made by his father and grandfather when they proposed to their respective spouses.
Steve is chosen to act as nursemaid for the attractive daughter of a visiting Danish dignitary who turns out to be only 17. The girl's energetic idea of fun brings Steve to his knees, as he searches desperately for a substitute escort.
Robbie is always forgetting to pass on Steve's telephone messages and to get back in his good graces, decides to take up his father's favourite sport. He figures it will get him out of the doghouse if he joins Steve in a father and son golf tournament.
Chip comes to the rescue of a trapped dog and receives a reward, which leads to new found popularity with his fellow members of the club that he and Ernie wish to join.
Steve has to fly to Washington and is given a top secret military project. Steve tells the Pentagon brass that he would attract the least attention by just doing the work at home. While Bub is just beside himself with curiosity, Chip suddenly becomes the target for security men.
Ex-thespian Bub laments that there hasn't been a member of the Douglas family in show business for over thirty years, so he is delighted when Chip is selected to portray an American Indian in a school play about Christopher Columbus.
While walking the dog through the park one night, Steve meets a lovely cabaret singer and before the evening ends he is out night-clubbing with her. Mike and Robbie feel they must intercede and protect Steve from a supposed matrimonial trap.
Steve eagerly anticipates his twenty fifth anniversary class reunion at Midwest University. Ignoring Bub's warnings that the old gang won't be as Steve remembers them, his enthusiasm increases when he meets the charming Heather Marlow, only girl in the class.
Mike and Sally try to discover the truth about marriage from two of their recently wed friends, and think twice about getting married and having babies when they help another friend's expectant wife whose time has come.
Bub is appointed chaperone to Robbie and his friends when they decide to have a costume party. Robbie feels it will dampen the party as Bub doesn't see eye to eye with them on the little matter of correct behaviour.
Robbie is chosen to help Americanize a traditional Chinese girl who is soon to meet her very hip Chinese-American fiancé. However, she is a girl so steeped in the traditions of her homeland that it seems unlikely she'll ever fit into American life.
The family is excited when Steve might travel to Hawaii on business, but there is dismay on their faces when the 'For Sale' sign goes up outside 837 Mill Street. Going on a trip to Hawaii is one thing, but could the entire family pack up and move there?
Chip believes in a magical stone frog, given to him by a lady from India and as coincidences stack up, the magic is hard to deny. The boy's belief causes some very interesting circumstances.
Bub wants to get back to the greasepaint, so he swaps jobs with an actress friend at the Playhouse theater who longs for a normal home life. Each is so envious of the other's life that they agree to switch roles for the remainder of the company's season.
Mike feels that Sally should learn how to fish, since she's joining a family of avid fishermen - Except that Sally really hates the pastime. How coincidental then that Mike hates bird watching as well.
Kimiko, a Japanese girl Mike met in Tokyo last year comes to town to test her old feelings for Mike before she can be sure she loves another. Although Mike is now engaged to Sally, could he still feel something for her?
Steve's high school sweetheart returns to town as a real-life Princess, complete with entourage and the Douglases are invited to a posh royal reception in her honor. However, Chip puts the wrong reply in his response and must try and retrieve it before the Princess reads it.
In order to get himself a date with an attractive magazine editor, Steve submits his house as an entry in her magazine's distinctive homes contest. He is very perplexed when she sends her business-like secretary instead.
The town of Bryant Park takes sides violently when it is proposed to cut down the tree which stands outside of Robbie's girlfriend's home. The Douglas family are soon involved as Bub joins a women's group in the neighborhood to save his favorite tree from being torn down.
Disciplinarian Mrs. Proctor, Robbie's awful history teacher, breaks a leg and the replacement they receive is even worse. She is a charming, but inexperienced girl who earns her first battle star when she first encounters Robbie's class.
Anxious to get married, but unable to afford an apartment, Mike suggests that he and his fiancee Sally move in with him and his family. Bub has to continuously change plans for a shower for Sally and Mike when she and Mike keep changing their future wedding plans.
Mike and Chip take part in good deeds -- Mike goes with his fellow U.S. Air Force Reservists to deliver ten thousand dolls to children in a South American disaster area. Mike meets a mute girl and tries to collect money for an operation she desperately needs. Meanwhile Chip becomes household slave of the demanding Mrs. Sowerby.
When Robbie's team gets slaughtered one too many times, their keenest fan Lissa Stratemeyer gets her girlfriends to ignore the boys for the victory rally until they do something about the score and break their losing streak.
Aspiring song writers Mike and Robbie decide to take a song they wrote to New York City and present it to a publisher. A friendly cab driver helps them in their quest and the publisher gives them both some good advice before they head home.
Mark Twain's stories inspire Chip, Ernie and Melinda to re-enact the adventures of Huckleberry Finn, Tom Sawyer and Becky when the youngsters run away from home to the river where they find a few adventures of their own.
Steve is roped into boarding a delinquent for just one week so the boys put on their armor and ready themselves for battle. When Steve is notified to fly out of town on business, the boys are left to deal with the delinquent themselves, not knowing they've mistaken him for somebody else.