While studying the economic history of Europe, French professor Jean d'Hayon became interested in political history. And unexpectedly for himself, in the middle of his life he became a writer, releasing novel after novel about the era of the Three Musketeers. He dedicated his famous series of historical detective stories about Louis Fronsac to this turbulent period in the fate of France. D'Ayon's hero has to constantly engage in investigations. He masterfully and enthusiastically solves the most complex riddles. And now, in some incomprehensible way, a police commissioner has been killed in a completely isolated room. Is there a connection between the cases the deceased investigated - the poisoning of an ordinary Parisian bourgeois, the attacks of the mysterious Flayer on Parisian women - and the death of the king? By the will of fate, Fronsac finds himself drawn into the intrigues and conspiracies of the highest nobility - the Important, as their contemporaries mockingly called them. But what is the purpose of the conspiracy of the Important - are they fighting for influence on Anne of Austria or planning the murder of Cardinal Mazarin?