During the Napoleonic Wars, a young officer discovers a manuscript related to the story of his grandfather, Captain Alphonse van Vorden of the Guard. Vorden—a man of honor and fortitude—is searching for a shortcut through the Sierra Morena.

At an inn, he accompanies two Eastern princesses. They treat him as a cousin and try in every way to seduce him. Soon he wakes up beneath a gallows from which two corpses hang…