University professor Marie-Claire encourages a student to continue her research on her thesis about desire. More particularly, on the physiological reaction of the cells of the human body during the sexual act, whether it’s performed with or without love.
Fascinated herself by this theme, the teacher, happy in her marriage as the mother of two teenagers, takes cells from her own body, as well as from those of her husband and her various partners. When a colleague, who is also her lover, is accused of sexually abusing a student, Marie-Claire jumps to his defense.
But her gesture has dramatic repercussions when the complainant turns out to be the girlfriend of a student with whom she herself has slept.