Nuit et Jour on AllMovie

Aimless young lovers Julie and Jack leave their provincial home and head for Paris to spend a year doing little more than wandering about and making frequent love. To support them, Jack gets a night job driving taxi. Julie does not work and while he works, she strolls the boulevards. Trouble comes when Julie falls for Joseph, a day-shift cabbie and begins a nighttime affair with him. At first Julie feels no guilt nor sense of betrayal, but as the intensity of the affair with Joseph, who has fallen deeply in love with her, increases, things get more difficult until Julie is forced to face up to her actions in the film's realistic finale.