Written by Tacchella and Danièle Thompson, the film is about two cousins by marriage who meet at a wedding and develop a close friendship.

After a raucous wedding reception with plenty of dancing and drinking, Marthe and Ludovic are left waiting for their respective spouses, Pascal and Karine, who are off having sex.

Some time later at a family gathering at Marthe's mother's house, Ludovic's teenage daughter, Nelsa, shows slides she took at the wedding—including compromising photos of Pascal and Karine.

Later that week, Marthe and Ludovic meet for lunch, buy bathing suits, and go swimming in a public pool.

Marthe and Ludovic playfully arrange to meet by chance at a restaurant with their respective families, to see how Pascal and Karine react.

Later that week, Marthe and Ludovic meet again at the swimming pool and acknowledge that their relationship is special and must remain that way, even if platonic.

At another family wedding, with Pascal and the groom's father fighting over a business deal gone wrong, Marthe and Ludovic decide to leave and spend the day together.

[5] At the Paris Theater in Manhattan, the film broke the attendance records set 10 years earlier by A Man and a Woman.

[8]In his review in The New York Times, Vincent Canby called the film "an exceptionally winning, wittily detailed comedy that is as much about family relationships as it is about love.

"[9] Canby goes on to write: In a rather startling way, no one seems to get seriously hurt in this film, even though there are deaths and profound disappointments, not because Mr. Tacchella takes a superficially rosy view of things, but because, with the help of his actors, he creates a group of characters who appear either to have inner resources or, like Karine, to be too self-absorbed to feel anything too deeply.