A genealogist and a cop: a great team for uncovering the origins of the crime. On a murder case, genealogist Margot Laurent teams up with Arthur Du Plessis, a young and self-assured cop. Who committed the murder? And why? A murder always has its dark side: a fabricated family history that becomes an urban legend. And who can claim that their family has no secrets? Margot and Arthur strip away the hidden mysteries to shed light on the murder. Arthur is the no-nonsense one, here to arrest the culprit, while Margot, the genealogist, is more interested in the past, in the prehistory of the murder, in what prefigured the tragedy before it happened. Between them, Margot and Arthur bring the events into focus. Here lie hidden family traumas, stories sometimes ignored by those who must endure the aftermath, which give multiple layers to the whodunnit.

Fired for insubordination, PJ Antoine Verlay, good cop but a blood strand and having difficulty working as a team, is attached to the OCBC (Central Office for the fight against Traffic in Cultural Goods) thanks to the intervention of the commander Pardo, his friend who becomes, therefore, his new superior. A clever investigator, but a stranger to everything related to culture, Antoine will have to work with Florence Chassagne, renowned art historian, who lives, speaks and breathes culture, to the point that - fruit of her great imagination - it happens to her in the midst of daydreams, to see and talk to the great artists who have disappeared as if they were familiar to her.