Paris and its suburbs. Two stories, four girls, four boys, on one summer day that will change their lives forever.

In the first part, L’ami du dimanche, Milena and Lucie, colleagues at work, take advantage of a sunny Sunday to go swimming at the leisure centre in Cergy-Pontoise. Meeting Jean changes the course of the day and upsets their developing friendship.

In the second part, Hanne et la fête nationale, Hanne, a Norwegian exchange student in Paris, suddenly finds herself having to deal with three men. As the July 14 festivities are at their height, Andrea, Roman and Sipan spend the evening at the Cité Universitaire with Hanne and Salomé, her next-door neighbor in the dorm.