| Director | Alan Alda |
|---|---|
| Budget | $6.5 million |
| Box office | $50.4 million |
Three middle-class married couples – Jack and Kate Burroughs; Nick and Anne Callan; Danny and Claudia Zimmer – live in New York City and are close friends. Jack is a moralistic lawyer, Kate a Fortune magazine editor, Nick an insurance salesman and estate planner, Anne a housewife and photographer who photographs mostly vegetables, Danny a cheap dentist who displays symptoms of obsessive-compulsive disorder and hypochondriasis, and Claudia a blunt-spoken Italian painter. Quarterly (in each of the four seasons), the three couples go on vacations planned by Kate.
In May, the six friends go to Nick's and Anne's weekend cottage in the forest to celebrate Nick and Anne's anniversary. The husbands cook Chinese food and go bike racing, while the wives discuss Anne's latest photos.
While gathering firewood, Nick reveals to Jack how unhappy he is being married to Anne so he plans to divorce her, wanting a woman who can excite him. When Jack asks if another woman is involved, Nick denies it. That night, Kate is devastated when Jack tells her of Nick's intentions, and both worry about Anne.
Nick has separated from Anne and is dating Ginny Newley, a younger, beautiful, naive woman. The Burroughses and Zimmers are not impressed with Nick giving Ginny a new present daily and her believing all of his stories. All three couples, except Anne, spend the summer on a sailboat around St. Thomas.
During their vacation, the sailboat gets stuck in a sandbar, and the Burroughses and Zimmers are unable to sleep well due to Nick and Ginny's loud sexual encounters every night. When the group gets the sailboat unstuck and resumes the journey, the Burroughses privately discuss how Nick and Ginny's relationship is affecting the others. After witnessing Nick and Ginny skinny-dipping in the sea, the Zimmers join them.
In fall, the group rides Danny's new Mercedes-Benz to Connecticut to spend Parents' Weekend with two of the couples' daughters: Beth Burroughs and Lisa Callan. While checking in to the university inn, the couples awkwardly encounter Anne, who is also there to spend time with Lisa. Kate and Claudia apologize to her for not inviting her to their previous vacations, as Nick is bringing Ginny. Anne, who has become depressed over their separation, tells them she is moving on by trying new things such as vacationing in Czechoslovakia and adopting a snake. Beth reveals to her mother that despite being childhood friends, she and Lisa are no longer close.
Meanwhile, Danny has become increasingly upset with Claudia's insensitivity to others, which she blames on her Italian heritage and refuses to apologize. Nick cannot cheer up Lisa, who has become withdrawn and unhappy over her parents' separation. Danny reveals to Jack that Nick is a womanizer, having secretly cheated on Anne with multiple other women. During a game of soccer, Jack bruises his knee from tackling Nick, with whom he is becoming estranged. That night, the Burroughses fight about Nick and Ginny, and Kate confesses she hates planning the group's quarterly vacations.
The Callans have divorced, with Nick marrying Ginny and Anne becoming a magazine photographer. In winter, the three couples vacation at a ski resort, where they rent a lodge. A skiing match between Nick and Jack results in the former breaking an ankle and the latter tearing his ligament. To cheer everyone up, Ginny invites the others to a bar. When Danny's friends laugh at his hypochondria, Ginny surprisingly defends him.
When they return to the lodge, Kate inadvertently upsets Ginny by saying she will never understand the group. Ginny calls them out for not accepting her, then leaves the lodge. Despite his lack of concern, Nick reveals that Ginny is pregnant. The group argues again, culminating in Jack breaking some things before Kate calms him down.
When Ginny still has not returned by morning, Danny goes to look for her. He finds her jogging but accidentally falls through thin ice. Ginny runs back to the lodge to get Danny help. Driving Danny's Mercedes-Benz to rescue him, they carelessly drive it onto the ice, it falls through, quickly sinking under the surface. The friends reconcile and walk back to the lodge, with Kate jokingly saying they should all return next winter.