The central conflict arises when the beautiful and calculating Lizzie Eustace claims ownership of a valuable diamond necklace that her late husband's family insists belongs to the estate. Lizzie navigates the rigid social hierarchies of Victorian England, utilizing her charm and manipulative tactics to secure her financial future against the formidable legal opposition of the Greystock family. The narrative framework employs a third-person omniscient perspective, allowing the reader to observe the internal motivations of the various suitors, lawyers, and socialites caught in the web of the diamond dispute. The story operates within the constraints of 19th-century inheritance laws and the strict social expectations placed upon widows of the aristocracy. The primary forces opposing Lizzie include the persistent legal representatives of the Eustace estate and the skeptical members of high society who view her claims with suspicion.

Readers and critics frequently highlight the novel's sharp wit and Trollope's ability to create a protagonist who is simultaneously frustrating and compelling. Discussion often centers on the moral complexity of Lizzie Eustace, as she challenges the traditional expectations of a Victorian heroine through her blatant self-interest. The pacing is noted for its deliberate, methodical approach, which allows for a deep immersion into the social and legal intricacies of the era. Many readers appreciate the balance between the central legal mystery and the broader commentary on the vanity and greed prevalent in the upper classes. The work is widely regarded as a significant study of character psychology within the framework of a traditional social novel.