To find out who the father of her unborn child is, the widowed and disowned Marquise of O. places a newspaper advertisement seeking this man and promises to marry him. Count F. responds to the ad; he had saved the widow from being raped by soldiers during the siege of the city a few months earlier. Filled with disgust over the Count's actions, she initially refuses to marry him, but eventually agrees under the condition that they live separately. However, the Count does not give up and courts the widow again after a few months, leading to a second, genuine wedding. The novella, published in 1808 and adapted into a film in 1976, is structured like a crime novel. The reader gradually learns the background behind the Marquise of O.'s unusual newspaper advertisement.