Une ténébreuse affaire (English "A Murky Business" or "A Historical Mystery") is a novel by Honoré de Balzac, published in 1841.

Her cousins the Simeuse twins, and Robert and Adrien d'Hauteserre, who are all exiled aristocrats, return secretly to France to take part in the plot, and she helps to hide them.

However the plot is discovered, and Corentin and Peyrade who are spies working for Police Minister, Joseph Fouché travel to Aube to find the conspirators.

Just before Napoleon's coronation as Emperor, an application is made by Monsieur d'Hauteserre on behalf of his sons and the Simeuses that their rights as citizens should be restored.

This is granted by Napoleon during a cabinet meeting, and so the two pairs of brothers emerge from hiding and settle in Laurence's home at Cinq-Cygne.

Laurence's elderly relative Marquis de Chargebœuf urges the young men to serve in Napoleon's army in order to win favour.

Henri de Marsay who is present at the party explains to the other guests the reason for this, and gives details of Malin's involvement in an unsuccessful political plot with Talleyrand, Fouché, and others against Napoleon in 1800, and how his efforts to cover it up had led to the problems that Laurence experienced.

Balzac's father, who was an official in Tours at the time knew Clément de Ris, and passed on his knowledge of the incident to his son.

Hunt wrote "One of Balzac's most intense convictions was that in the sphere of political activity principles of private morality go to the wall.

This questionable maxim lies behind a historical novel - Sur Catherine de Médicis - on which he was at work during a long period, from 1830 to 1843.