At the initiative of Nath, an environmental activist and Laurent's girlfriend, the group of friends Thomas, Laurent, Marc and Aude, will embark on a punitive expedition to a cosmetics laboratory. A series of incidents will cause an inexplicable phenomenon, a lightning bolt that strikes Thomas and causes a strange burn on his arm. And the next day, Thomas, stunned, wakes up transformed into a girl... Justin, his little brother, and Aude, his best friend, will be in on the secret and help Thomas hide this strange phenomenon.