On a foggy December night, a young woman is fished out of the Seine near the Pont-Neuf. Naked, amnesic, but alive, she was taken to the infirmary of the Paris police headquarters... from where she escaped after a few hours.

DNA analysis and photos reveal her identity: she is the famous pianist Milena Bergman. But it is impossible, because Milena died in a plane crash, more than a year ago.

Raphaël, her former fiancé, and Roxane, a cop weakened by her recent dismissal, become fascinated by this investigation, determined to shed light on this mystery: how can one be both dead and alive?