Marc Thiriez, a middle aged Parisian, asks his wife if he should shave off the moustache he has sported for most of his adult life. His wife, Agnès, wryly comments that she wouldn't recognize him without it, yet as she leaves, Marc shaves the moustache off. Upon her return, Agnès is angry Marc did not let her in the door when she rang; Marc lies and says he broke his shoelace. Marc attempts to surprise her with his clean-shaven face, but gets no reaction. In the car Marc asks his wife if she notices anything. She does not respond, wanting to know if he thinks she is dressed too sexy for the party. Later that evening, as the two visit their friends Serge (Agnès' first husband) and Nadia, Serge tells a funny story from his marriage to Agnès, how she was sneaky and refused to admit it, even when found out. Agnès again denies the sneakiness. Frustrated that Serge and Nadia also do not notice that Marc has shaven his trademark moustache, Marc fights with Agnès in the car as they return home, frightening her. As they lie in bed that night, another fight over the moustache ensues as Agnès tells Marc he's never had a moustache and that she fears for his sanity. Agnès phones Nadia, who claims Marc has not had a moustache in fifteen years. Agnès takes a sleeping pill to sleep.