Honoré de Balzac 
The Duchesse of Langeais [PDF ebook] 

La Duchesse de Langeais is an 1834 novel by French author Honoré de Balzac (1799-1850) and included in the Scènes de la vie parisienne section of his novel sequence La Comédie humaine. It is part of his 1839 trilogy Histoire des treize: Ferragus is the first part, Part Two is La Duchesse de Langeais and Part Three is The Girl with the Golden Eyes. It first appeared in 1834 under the title Ne touchez pas la hache (Don’t Touch the Axe) in the periodical L’Écho de la Jeune France.
General Armand de Montriveau, a war hero, is enamored of Duchess Antoinette de Langeais, a coquettish, married noblewoman who invites him to a ball but ultimately refuses his sexual advances and then disappears. Assisted by the powerful group known as The Thirteen, who subscribe to an occult form of freemasonry, General Montriveau finds the duchess in a Spanish monastery of Discalced Carmelites under the name of Sister Theresa.