Émilie, Audrey Tautou the co-owner of a hair salon in a French seaside town, receives an anonymous love letter from her employee Jean, Sami Bouajila the salon's shy handyman. Unimpressed, she throws the letter away but later retypes it and sends it anonymously to her mother Maddy, Nathalie Baye who has been depressed since her husband left her for a younger woman. After witnessing Jean arguing in Chinese with two women, Émilie learns that he is a Harvard graduate and polyglot who previously worked as a UNESCO translator; he explains that he took the handyman job because he was fired from UNESCO after suffering a nervous breakdown. Feeling unsettled by his high level of education, Émilie struggles to assign him menial tasks and only communicates with him through her staff.
Maddy, feeling instantly reinvigorated by the love letter, eagerly awaits a new note from her secret admirer, prompting Émilie to write another anonymous letter to her mother, but Maddy finds it uninspired and emotionally cold and becomes convinced that her admirer has fallen out of love with her. To avoid Jean, Émilie sends him to run errands, including posting the mail. When he runs out of stamps, he personally delivers a new anonymous fake love letter from Émilie to Maddy, unaware of its contents. Maddy sees Jean placing the letter through her letterbox and follows him back to the salon. She deduces that he is her secret admirer and, despite Émilie's protests, flirts with him.
That evening, Émilie visits him and, after explaining everything to him, offers to pay him to pretend to be Maddy's admirer and take her out on a few dates, but he refuses. Upset, Émilie writes Maddy an anonymous letter spurning her. The next day, Maddy goes to the salon and confronts Jean with the letter, slapping him in the face before storming off. Knowing that Émilie wrote the letter, Jean follows Maddy home and attempts to explain himself, but she rebuffs him. After Maddy receives a call from her ex-husband, who reveals that his current wife is pregnant, she breaks down in tears and is consoled by Jean.
Jean agrees to a date with Maddy. Afterwards, Maddy calls Émilie and cheerfully discusses the date; when Maddy mentions that Jean recited the final portion of the first letter from memory, Émilie realizes that he was the one who wrote the anonymous letter. The next day, Jean shows up drunk at the salon and flippantly takes €600 from the cash register as payment for taking Maddy out. Émilie confronts him about his unpleasant and cynical behavior when she knows he is the opposite. She apologizes to Jean for forcing him to court her mother and promises to tell her the truth. He announces he is leaving town the next day, and they bid each other a tearful goodbye.
Having overheard Émilie and Jean's conversation at the salon, Maddy falls out with Émilie. Feigning ignorance, Maddy invites Jean over for a romantic dinner and hands him an envelope of money, lying that Émilie left it for him. Maddy later seduces Jean and they kiss, which is witnessed by Émilie who is standing outside her mother's house. The next day, Jean moves to Paris.
Some time later, Maddy receives an invitation from her ex-husband to his art exhibition in Paris. Knowing that Émilie will also be there, Maddy sends Jean an anonymous letter inviting him to the exhibition. Jean, thinking that the letter is from Émilie, attends the exhibition and asks her if she wrote the letter. Seeing that Maddy is watching them from a distance, Émilie replies that she did write it, and the two kiss.
