This is the story of two law enforcement officers who work together to investigate serious crimes. Captain Raphaëlle Costa goes to the archives to gather information on a case that interests her. There, she meets a young and quite unusual girl named Astrid. Astrid has an excellent memory and analytical abilities, unlike Raphaëlle, who relies more on her professional intuition. The women decide to work as a team. They become partners: Astrid et Raphaëlle.