Mélissa, a brilliant investigator of Martinican origin and single mother of two teenagers, unwittingly finds herself at the head of a crime unit on an island - Martinique - where she has never set foot. Gaëlle has lived there since childhood and knows the territory like the back of her hand. She's spontaneous, daring, independent and doesn't hesitate to speak her mind. One embodies law and order, while the other represents law and chaos.