La Duchesse de Langeais (The Duchess of Langeais) is an 1834 novel and is part of of the Scènes de la vie parisienne (Scenes from Parisian Life) section of La Comédie humaine. It is also part of a trilogy, referred to sometimes as The Treize. (The other two novels in the trilogy are Ferragus, which is the first part, and La Fille aux Yeux d'Or (The Girl with the Golden Eyes), which is the third part.
In the novel a general, a war hero, falls for the Duchess de Langeais, a married noblewoman who invites him to a ball but ultimately refuses his sexual advances and then disappears. Assisted by a powerful group known as The Thirteen, the general locates her in a Spanish monastery.