François Sentinelle has two lives. By day, he is the most famous cop of Réunion Island, known for his tough methods and flowery shirts, pursuing criminals in his famous yellow defender. But the rest of the time, Sentinelle is also a charming singer.

Marianne, a beautiful woman from Réunion Island destined for a great career as a mermaid swimming champion, has been living in hell since a huge beard began to grow on her face following a psychological shock. Rejected and unable to bear her image any longer, she will try everything to get rid of this unlikely hairy attribute, but will end up facing something far more monstrous than herself.