David Zimmerman, a Parisian photographer who has just broken up with his partner, is dragged by his insistent best friend to a New Year's Eve party. The presence of his ex doesn't bode well for a memorable evening, but he suddenly discovers among the guests the face of a girl he photographed months earlier: mesmerized, he follows her, and without exchanging a word, they make passionate love. The next day, when he wakes up at home, still dazed, he discovers that his body has transformed into that of the girl and that she has disappeared without a trace. In a strange body, terribly confused and frightened, David asks himself many questions. What exactly happened? Who was the girl? How can he get his body back? And, above all, is he still the same person?