Lady Susan by Jane Austen is a short epistolary novel (written as a series of letters between multiple characters). It was possibly written in 1794, but never submitted for publication by the author. It was finally published in 1871, a long time after her death.
Lady Susan has the distinction of being unlike any other famous novel in 19th century literature. It certainly has no parallel among Jane Austen’s novels. While the protagonists of her novels are generally virtuous and selfless, Lady Susan is selfish, deceitful and crafty in nature. Recently widowed, and in spite of having a teenage daughter, Lady Susan has no qualms about playing with the emotions of men much younger than her age; or having a relationship with a married man. She has the quality to bring any man under her spell, and also knows how to use this quality effectively.
Although the ending has a traditional reward for morality, Lady Susan is treated much more leniently by Jane Austen than she probably deserves.