After discovering their parents were unmarried at the time of their birth, two sisters find themselves suddenly disinherited and forced to navigate a hostile social landscape. Magdalen and Norah Vanstone must confront the legal and social consequences of their illegitimacy, which strips them of their inheritance and social standing. Magdalen, the more impulsive of the two, adopts various disguises and schemes to reclaim the family fortune, while Norah attempts to maintain a sense of propriety. The narrative utilizes a third-person perspective to examine the rigid constraints of Victorian law and the desperation of those cast out by societal norms.

Discussion often centers on the novel's bold critique of Victorian social conventions and the legal status of illegitimate children. Readers frequently highlight the complexity of Magdalen Vanstone as a protagonist who defies traditional gender roles through her calculated schemes. Critics often note the shift in Collins's focus from pure mystery to a more pointed social commentary regarding the vulnerability of women in the nineteenth century. The pacing is frequently praised for its ability to maintain tension through the sisters' evolving circumstances and moral dilemmas. Many readers find the work to be a significant example of the sensation genre that balances character development with a compelling narrative arc.