La Moustache opens with Marc Thiriez, a middle aged Parisian, taking a bath and asking 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. 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 (Agnes' 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 Agnès. As they lie in bed that night, another fight over the moustache ensues as Agnès digs in her heels and tells Marc he's never had a moustache and that she fears for his sanity. Agnès phones Nadia and Nadia claims Marc has not had a moustache in fifteen years. Agnès takes a sleeping pill to sleep.
Marc finds a photo album of pictures from their holiday in Bali, all of which show him sporting his moustache. When he confronts Agnès with these pictures, she ignores him and changes the subject, leaving him even more confused. She suggests Marc see a psychiatrist whom her friend François knew. Marc tries to make the best of his situation, but grows more paranoid and confused when even his co-workers don't acknowledge that he has shaven his moustache. He smokes a cigarette and his co-worker tells him he is fool for starting up again.
His wife is upset at the soccer team and yells at the TV. She is upset when she finds Marc has taken up smoking again. They go out and Agnès insists on buying Marc a brightly patterned jacket ("a clown's jacket" as Marc describes it). Agnès orders a cigarette at dinner, saying they will quit together again later, and cries as she smokes and drinks.
As Marc gets his photograph taken for his work badge, he asks a woman who is also getting her photograph taken if she notices a difference between the photograph that was just taken and his photograph which appears on his I.D. card. She says the moustache is different, and Marc asks her several times if she is sure he has a moustache in the photograph. She confirms this, which leaves Marc more baffled. He returns home early from work.
Marc checks his answering machine to find a message from his father. Agnès' friend Bruno calls and Marc tells him to stop kidding him about his moustache. Bruno assures Marc that Marc has not had a moustache in fifteen years. Marc hangs up on him. In the kitchen, he tells Agnès to call his parents and tell them that he won't be able to come to their house for dinner the next day. Agnès calls Marc's mother, but gently reminds Marc that his father is dead and has been so for a year. Confused, Marc speaks of their best friends Serge and Nadia, to which Agnès replies that she doesn't know who they are and that Marc must be delusional. Very upset and slowly losing his grip on sanity, Marc goes to bed, and Agnès gives him a sleeping pill.
Marc awakes to hear Agnès and Bruno planning to have Marc committed to a psychiatric hospital. Marc quickly dresses and flees the house. In a taxi, he attempts to find his mother, yet due to the sleeping pill and the heavy rain, he cannot find the house in which he grew up. Marc tries to call his mother, but the number he dials is not a valid phone number. He calls Agnès, tells her he is at his mother's, and asks her to pick him up. When Marc sees Agnès and Bruno leave his apartment to pick Marc up, he rushes inside, grabs his passport, puts on shoes, breaks his shoelace and leaves. He flees to Hong Kong, the first available flight out of Paris. His passport photo sports a moustache.
Marc journeys through Hong Kong, traveling back and forth on the Star Ferry all day. After the ferry stops for the night, he pays local sailors to take him with them on their boat. They agree, and Marc arrives at an unspecified village in China (filmed in Ko Lau Wan, Sai Kung Peninsula, Hong Kong). Marc stays at a hotel there for a period of time, becoming known with the locals, and regrows his signature moustache.
Marc arrives back at the hotel to find Agnès awaiting him, as though she has been with him the entire trip. Agnès makes fun of his brightly patterned jacket and asks him why he bought it, hoping he will not wear it in Paris. They go out to a casino and meet new friends that Agnès knows but Marc does not. The male half of the couple shows him recent photos of the four of them in which Marc has a moustache. Marc has no memory of the event, but the pictures are whisked away before he can examine them closely. Agnès notices Marc's irritation and says if he doesn't like their new friends they don't have to ever see them again when they get back to Paris.
In an ambiguous ending, Agnès suggests that Marc shave his moustache so she can see him without it at least once. He does so, and Agnès comments upon how good he looks without it. Whether this final scene was meant to be what really happened or was just an idealised dream of what Marc wished had happened is unspecified.
La Moustache captures an element of suspense, though the actions and plot are ambiguous. Many critics have said that the film's events are not literal, but metaphorical and are symbolic of Marc's loss of identity (or of a possible mid-life crisis).Vincent Lindon – Marc Thiriez
Emmanuelle Devos – Agnès Thiriez
Mathieu Amalric – Serge Schaeffer
Hippolyte Girardot – Bruno
Cylia Malki – Samira
Macha Polikarpova – Nadia Schaeffer
Fantine Camus – Lara Schaeffer
Denis Ménochet – The server
Frédéric Imberty – Café manager
Brigitte Bémol – Policewoman