Lady Susan (version 2)

Lady Susan Vernon, a recent widow, visits the brother of her recently deceased husband and his wife, Charles and Catherine Vernon, with little advance notice, at their country residence. Catherine is displeased, as Lady Susan had tried to prevent her marriage to Charles and her unwanted guest has been described to her as "the most accomplished coquette in England". Among Lady Susan's conquests is the married Mr. Manwaring. Lady Susan had been staying at the Manwarings' residence but had to leave rather abruptly after she seduced both Mr. Manwaring and his younger sister's fiancé.
Catherine's brother Reginald arrives a week later, wanting desperately to meet the Lady Susan that everyone speaks so poorly of, and despite Catherine's strong warnings about Lady Susan's character, soon falls under her spell. Lady Susan toys with the younger man's affections for her own amusement and later because she perceives it makes her sister-in-law uneasy. Her confidante, Alicia Johnson, to whom she writes frequently, recommends she marry the very eligible Reginald, but Lady Susan considers him to be greatly inferior to Manwaring.
Frederica, Lady Susan's 16-year-old daughter, tries to run away from school when she learns of her mother's plan to marry her off to a wealthy but insipid young man she loathes -- the previous fiancé of Mr. Manwaring's daughter, who is still in love with Lady Susan. She also becomes a guest at Churchill. Despite how poorly Susan speaks of her daughter, Catherine comes to like Frederica -- her character is totally unlike her mother's -- and as time goes by, detects Frederica's growing attachment to the oblivious Reginald.
Later, Sir James Martin, Frederica's unwanted suitor, shows up uninvited, much to her distress and her mother's vexation. When Frederica begs Reginald for support out of desperation (having been forbidden by Lady Susan to turn to Charles and Catherine), she causes a temporary breach between Reginald and Lady Susan, but the latter soon repairs the rupture.
Lady Susan decides to return to London and marry her daughter off to Sir James. Reginald follows, still bewitched by her charms and intent on marrying her, but he encounters Mrs. Manwaring at the home of Mr. Johnson and finally learns Lady Susan's true character. Alicia writes that her husband has forbidden her to meet with or write to Susan anymore, at the threat of them moving full-time to the countryside. Lady Susan ends up marrying Sir James herself, and allows Frederica to reside with Charles and Catherine at Churchill, where Reginald De Courcy "could be talked, flattered, and finessed into an affection for her."