Directed by Melvin Frank, who co-wrote it with producer Norman Panama, this romance drama was originally written as a Brief Encounter (1945) type movie for James Stewart and Olivia de Havilland. Eight years later, it was modified into a more comedic look at two persons frustrated by their attempts to have an affair. Hence, it stars Bob Hope and Lucille Ball; Ruth Hussey and Don DeFore play their spouses. Louis Nye and Philip Ober also appear. Writers Frank and Panama earned an Academy Award nomination for their story and screenplay; the film's title song, and B&W Art Direction-Set Decoration and Cinematography were also nominated. Edith Head's and Edward Stevenson's B&W Costume Design won the Oscar.
The Gilberts, the Weavers, the Masons and the Busbees are middle class, suburban married couples who socialize at the same country club and even take vacations together to save expenses. Larry Gilbert (Hope) and Kitty Weaver (Ball), who don't particularly get along, are two in this group. However, the film begins with Kitty getting off a plane where she's greeted by Larry, who kisses her affectionately. These two have finally decided to consummate their extramarital affair which began on one of those shared vacations. While Larry goes to get their luggage and the rental car, Kitty has time to reflect on how she and he happen to be in Monterey together:
The country club's annual golf tournament is over and Larry is its emcee. He's giving out awards, one to Hamilton Busbee (Nye), while delivering the same tired jokes he always does, evoking polite chuckles from the members. Kitty, however, is bored enough with the routine to inadvertently, yet rudely, yawn during the proceedings. Naturally, this upsets Larry who complains about her behavior to his dependable wife Mary (Hussey) on the way home. Meanwhile Kitty, who'd been sitting with Mary, Doc Mason (Ober) and his wife Connie (Marianne Stewart), is berating her husband Jack (DeFore) for leaving her alone to gamble away $200 at a craps game. Once they're home, Jack is able charm Kitty into getting ready for some romance, but she is disappointed to find he's fallen asleep by the time she's ready. The Gilberts are able to carry on a conversation getting ready for bed by sharing the same sink, but then learn from their babysitter (Louise Beavers) that one of their two boys is getting sick. After a visit from Doc Mason, Mary tells her husband that she won't be able to join him for a couple of days on their Acapulco vacation, planned with the Masons and the Weavers. The next morning, Jack gets a call from his boss that means he'll have to miss the first few days as well.
On the flight to Acapulco, Kitty learns that Larry paints, which begins to shatter her preconceived notions about the man. The Masons are quickly stricken with food poisoning so that Kitty and Larry have only each other with whom to socialize. While initially this is a daunting and undesirable option, they each decide that being together would be better than being alone. They catch a huge marlin while deep sea fishing, after which they celebrate by embracing. Pulling away, each has begun to think of the other differently. Their new relationship begins slowly, with Kitty and Larry both starting and stopping themselves from pursuing something more. When they learn that their spouses will not be joining them and the Masons sickness persists, they end up spending the entire week with one another, laughing most of the time. At the end of the trip, it's clear that they've fallen in love with one another, but they part and go their separate ways.
It probably would have just been a "shipboard romance" but, because of their country club clan, Kitty and Larry find themselves in social situations together that include dancing. When combined with the unromantic and humdrum home lives (including Larry being ignored by his kids, who ask mom for everything), the two mutually agree to meet again. This proves to be too dangerous or complicated - one involving a door-to-door cleaner and another a seedy hotel manager.
Before she'd left for the tryst, Kitty had left her husband a "Dear John" letter, telling him everything. When she tells this to Larry, he is upset, but accepts their situation. He then begins to tell Kitty what will happen next, acting like the man in charge she hadn't seen, and it's clear that this will be the beginning of the end of their relationship.
The film's story devolves into a series of slapstick scenes which aren't as funny as the writers had intended. It rains which causes the couple's convertible and idyllic "cabin in the woods" to flood. This, along with planning their divorces, puts Kitty and Larry in situations and discussions which might normally take years to come about, effectively forcing them to learn more about the other quickly. In other words, they experience the opposite of what they had probably imagined their liaison would be like. Both are disillusioned and perhaps a little relieved at the same time that they haven't yet consummated their relationship. On the radio, they hear that the weather has caused the closing of the sky slopes where Kitty's husband had been with their child, so she and Larry decide to beat them back home to intercept her letter. Unfortunately, they run into Hamilton and his wife at the airport, which foils their plans. Kitty actually arrives home after Jack has read the letter, even though he doesn't let her know it. She speaks hopefully of their future together and he discards the letter in the fire joyfully - a new beginning! Mary, unawares, receives Larry home as lovingly as usual and chuckles at his implied idea that he might ever have an affair.