During a performance at the Château de Blois, an industrialist is murdered as he plays the role of Henri III. Arthur, the young actor playing the Duke of Guise, becomes prime suspect. Police Captain Alice Deschamps heads the investigation with her ex and Arthur's father, Detective Inspector Denis Frécant.

Captain Hannibal Pennac is retired and dreams of reconciling with his daughter Annabelle, also a police captain, who has just been transferred to Montpellier. But Anabelle is angry with her father and does not want to talk to him, because he left her when she was 6 years old. However, a mysterious case will force them to unite and Annabelle will have no choice but to work with her father.