Gopher convinces Julie to pose as his girlfriend to impress his abrasive fraternity brother. Complications arise when the two longtime friends begin falling for each other. Four men who served together in Korea hold their reunion on the ship. The other men ask a widowed cabin stewardess to woo their gung-ho buddy as a distraction, as he won't talk about anything but the army. A single mother-to-be finds romance with a fellow passenger, but fears that he won't react well to the news of her pregnancy.
Vicki tries to play matchmaker for Capt. Stubing and Emily, whose husband still plans on winning her back. Gopher lands in a Curacao jail after Doc sends him on a wild goose chase so that he can get cozy with the marriage-a-thon judges. Carl and Mary Ann decide that they were wrong to interfere with their kids' wedding plans; but their new romance drives a wedge between the couple. Mary considers calling it quits with Tom, who is physically unable to say the words ""I do"" because of his subconscious fears about marriage. Emily accuses Marv of treachery after her fiancé suddenly reappears in Curacao and denies that he planned to leave her.
Famed author Brian Mallory gives three people free tickets to a Caribbean cruise. He then presents each of them--and Gopher--with gold coins. He explains that they are among the last people to have spent time with his nephew; and offers them $100,000 if they can track down the young man, who is believed to be on one of the islands the ship will be visiting. One of the passengers taking part in the quest is about to donate a kidney to his brother. A young woman follows him around and seems to take a special interest in everything he does. Mallory's wife finally grows tired of his aloof and cruel behavior toward her. She leaves him, and seeks comfort with Doc. An old friend asks Capt. Stubing to leave the ship to help him run his business. A jealous woman accuses Julie of trying to steal her fiancé, a man who was a casual acquaintance of Julie's in college.
As the search for Mallory's nephew continues, a mysterious man begins following Gopher, Marvin, Peter and Marcia and trying to thwart their efforts. Peter grows suspicious, and forces Mallory to come clean about his real reasons for wanting to track down his nephew. A suddenly repentant Mallory tries to make amends with his wife. Peter and his brother's fiancée grow attracted to each other. Capt. Stubing considers taking the job offer so that he can set aside more money for Vicki's college education. Julie's college friend and his crazy girlfriend continue to make her life difficult.
Isaac forces his friends to lie to his aunt about the quality of her performance in a local play, but his plan soon backfires. Two young people grow tired of their parents' constant attempts to push them together. A single mother hopes to find romance aboard the ship. She uses her son as a judge of character--she doesn't trust anyone who causes the baby to cry.
A kleptomaniac seeks the help of a psychiatrist to deal with her problem. He tries to distance himself from her when they begin falling for each other. Capt. Stubing's brother Marshall returns to the ship to get married. He has second thoughts when his fiancée reveals that she is broke, and is tempted by a past fling. A television star comes aboard the ship to accept a hero award on behalf of his character, a tough detective. A loudmouth begins harassing him, causing him to look bad in front of both his manager/girlfriend and number one fan Vicki.
The captain's ex-girlfriend comes aboard the ship and constantly makes passes at him because she feels neglected by her husband. A model pretends to be married to keep away annoying suitors. A man is convinced that a fellow passenger is an alien who turns into a plant every night.
Capt. Stubing decides to get Vicki a parrot for Christmas. Unfortunately, it hasn't been trained to talk, and Gopher and Isaac's efforts to train it prove disastrous. A stowaway convinces the crew that a playboy passenger is his father. A father and son, who haven't spoken for ten years since the younger man left their singing act to go solo, resist their wives' efforts to reunite them.
A couple takes a cruise to celebrate its 40th anniversary, but considers breaking up after the husband learns that his wife secretly invested money in the stock market for years. They are now wealthy, but he is furious because he could have retired much sooner. A woman tries to get her husband's attention by claiming that Doc made a pass at her during an examination. A man sneaks on the cruise because he doesn't believe the man travelling with his girlfriend is her brother. He convinces the passenger in the cabin next to theirs to let him stay by claiming to be with the CIA.
Gopher worries about meeting his pen pal Nicole, at first. Ned, married to workaholic Margo meets widow Kay, who's willing to take his wife's place. Helen evicts her handsome cabin mate Jack, who is desperate to find a room.
On a special cruise to Acapulco for a fashion festival, designers Geoffrey Beene, Halston, Bob Mackie and Gloria Vanderbilt play themselves. First of two parts. Paris: Robert Vaughn. Priscilla: Anne Baxter.
Conclusion. Julie has to substitute for her modeling friend at the fashion show. Lauren Tewes. Priscilla: Anne Baxter. Bob: McLean Stevenson. Paris: Robert Vaughn. Melissa: Cristina Ferrare.
Gopher's (Fred Grandy) aunt (Jane Powell), who Gopher doesn't know is a maid, comes aboard with her employer (Mary Wickes) and falls in love with a fellow passenger (Howard Keel); a playboy (Joe Namath) uses an old girlfriend (Karen Grassle) in a scheme on his best friend (Fred Willard); a baby boy is reluctantly abandoned by his father (Gary Burghoff), who is a ship's mechanic, and finds a sympathetic listener in a passenger (Belinda Montgomery), who is an old high school friend.
Julie (Lauren Tewes) has a run-in with a zoologist (Anthony Andrews), who turns out to be a passenger, and they butt heads. A young actress (Alison Arngrim) comes aboard and makes a fool out of Vicki (Jill Whelan). An estranged husband (William Christopher) and wife (Toni Tennille), one of whom is a neat-freak (Christopher) and the other a slob (Tennille), find themselves not only on the ship but in the same cabin
