Ousmane Diakité and François Monge are two cops with very different styles, backgrounds and careers. The unlikely pair are reunited once again for a new investigation that takes them across France. What seemed to be a simple drug deal turns out to be a much bigger criminal case wrapped in danger and unexpected comedy.
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.