While Sabine, a young archaeologist living in Bordeaux, inaugurates an exhibition in the crypt of the basilica of Saint-Michel, she discovers with horror a real skeleton wearing a red dress. This skeleton turns out to be her mother who died in a car accident 35 years earlier. But the next morning, the corpse of a man is found in similar circumstances - To solve this puzzle, Pierre, policeman of the Investigation Department and the young archaeologist will form a tandem before understanding that their own destinies are intimately related to this crazy story.