The exquisite young artist, Angélique (Tautou) sends a rose to her lover, the cardiologist Loic Le Garrec (Le Bihan). She is planning a future with him; the only problem is that he is married. But he has promised to leave his wife. Angélique is little troubled that the couple are expecting a baby and when the pregnancy is lost following an accident, she believes the day will be soon.

Her medical student friend, David, worries that she is being used and is appalled by the accumulation of disappointments and slights that Angélique must endure. She falls apart, neglects herself and the home and exotic plants that she has been watching for friends, but when she hears that Loic has been accused of assault by a female patient, she is utterly disbelieving. The patient is found dead and the doctor falls under suspicion.

Rapid rewind, and the movie begins again with the rose, and by repeating a handful of earlier scenes, retells the same events from the perspective of the doctor. He has no idea who is the sender of the rose, and as the flowers, notes, and gifts accumulate he grows more distracted, even angry, and his wife is suspicious.

It emerges that Angélique and Loic have barely ever spoken to each other and that she actually volunteered for house-sitting next door, in order to be close to him. The accident that caused the miscarriage was Angélique’s attempt to kill his wife by running her down with a motor scooter. The patient who charged the doctor with assault was wrongly mistaken by him for the secret admirer; he struck her out of anger and fear. She presses charges against him and pursues him through the courts until she is murdered by Angélique.

But the doctor knows none of that. When Angélique attempts suicide with gas, he saves her life and she is all the more smitten. Gradually the doctor realizes her real identity and the police link her to the murder. She is sent to a psychiatric hospital.

Years pass. Loic and his wife have two beautiful children. Angélique is finally discharged with reassurance that she will be well as long as she takes her medicine. In the final scene, the caretaker moves a large cupboard to find all the pills that she had been prescribed over four years pasted to the wall in a larger-than-life portrait of Loic.