In their 12th year of marriage Joanna and Mark Wallace are en route to the French Riviera for a business and social meeting with Mark's benefactor, architect Maurice Dalbret. Joanna and Mark had met years before on such a trip: Mark was then a fledgling architect hitchhiking through Europe, and Joanna was a music student on tour with a group of American schoolgirls. Their first encounter blossomed into romance, and by the time they reached the Côte d'Azur they knew they were in love and ready for marriage. Soon afterward they returned to Europe, but their motor trip was spoiled by their companions, the snobbish Cathy and Howard Manchester and their obnoxious daughter Ruth. Having learned their lesson, Joanna and Mark took their next vacation alone. Then, while Joanna was pregnant, Mark made a business trip by himself and experienced his first marital infidelity. Success came fairly easy for Mark, but his affluence and sense of self-importance alienated Joanna; and eventually she drifted into an indiscreet affair of her own. Driven to the brink of divorce, they are now forced to evaluate themselves and their marriage. Mutually willing to concede that they have changed but have grown maturely dependent upon each other, they are able to save their marriage.