Deception
The theme of deception is most obviously reflected in Lady Audley's change of identity. She is able to effectively hide the fact that she has previously had another name as well as a husband and child. This central deception requires her to execute a large number of smaller deceptions, such as tricking Sir Michael into thinking they are going to London to see Mrs. Vincent, when she really just wants to ensure that she doesn't risk meeting George and being exposed. While Lady Audley's deception is made possible by her quick thinking and calculated strategy, it also relies on the assumptions and stereotypes she is able to play with: because she seems beautiful and charming, people assume that she must be a good person. At the same time, deception is shown to be unsustainable. Even when she is at her most powerful, Lady Audley cannot totally execute her deception: small clues such as her depiction in the portrait and the way Alicia's dog growls at her imply that her true nature cannot totally be hidden. It is also interesting that while Lady Audley is the primary agent of deception in the novel, it turns out that she herself is being deceived the whole time. Luke allows her to believe that she has killed George; because he tricks her, he gains a great deal of power over her.
Mobility
Mobility is a theme with two meanings in the novel. It refers to both people's ability to literally move from place to place, and to symbolically move between different social positions. Both of these kinds of mobility create disorder and instability in the novel. It is George's decision to uproot his life and go to Australia that triggers the cascade of future complications. Lady Audley's reinvention of herself is only possible because she can readily escape to another place. The crisis of George's disappearance is triggered by the various possibilities of where he might have gone. Because so many of the mysteries of the novels are caused by geographic mobility, Robert has to be on the move almost constantly to solve the case. At the same time, several of the less privileged characters in the novel (Phoebe, Luke, and Lucy) work to try to advance their money and social position, hoping to move to a better life. Lyn Pykett suggests that "Lady Audley’s self-proclaimedly heartless attitude to her situation is, from one point of view, simply a more than usually honest assessment of the nature of the choices open to the would-be genteel woman" (93). The idea of individuals trying to rise to higher social positions was typically viewed with suspicion in the Victorian era, and Braddon presents social mobility as a disruptive force in the novel.
Femininity
The idea of characters conforming or failing to conform to expectations of femininity is a key theme in the novel. The Victorian period was a time that both restricted the options available to women and also placed rigorous demands on their appearance and behavior. Women were expected to be docile and submissive, well-mannered and graceful, and charming and pleasant companions without having desires or expectations of their own. At first, Lady Audley seems to be a model of Victorian femininity: she is beautiful, innocent, sweet-tempered, and devoted to her husband. However, it eventually becomes clear that Lady Audley is manipulating these conventions as a way of disguising who she actually is. As Laurence Talairach-Vielmas summarizes, "Braddon deflates the icon of ideal femininity in order to disclose the artificiality of the nature of woman" (121). Her actions would appear particularly heinous to a Victorian audience because they involve not only violence, but also abandoning her husband and child. While Lady Audley shows how femininity can be used as a disguise, other female characters also challenge expectations around femininity. Alicia Audley is athletic, outspoken, and strong-willed; while she is a morally superior character, she is also less attractive to Robert as a result. Even Clara Talboys, who is beautiful and with whom Robert falls in love, insists that she can behave like a man and pursue vengeance for her brother if necessary.
Misogyny
Misogyny, or the hatred of women, is represented in Robert's complex feelings about women over the course of the novel. As he becomes more convinced that Lady Audley murdered his friend George and is now deceiving everyone about her true nature, Robert wonders whether all women are inherently deceitful and untrustworthy. Even as he begins to feel attracted to Clara Talboys, he resents her for pressuring him into continuing to pursue the mystery of George's disappearance, which is a frustrating and exhausting task. Robert actually feels that women have too much power, and are capable of tricking and manipulating men. By the end of the novel, when Lady Audley has been rendered helpless and he has asserted his own power, Robert is able to take a more positive perspective, and ends up happily married to Clara.
Madness
Madness is a very important theme in the novel, because it is often uncertain who is mad, and what definition can be used to label them as such. When Robert first starts to consider the idea that Lucy Audley may actually be Helen Talboys and that she may be responsible for George's disappearance, even he wonders if this idea is "mad," in the sense of being irrational or improbable. The theme takes on more sinister connotations when Lady Audley threatens to accuse Robert of madness if he continues to imply that she is connected with George's disappearance. Because the criteria for diagnosing madness at this time was flexible, and someone could be institutionalized fairly easily, Robert knows that if Lady Audley successfully persuades his uncle that he is mad, he could be in real danger. The question of madness is most important in that it determines how responsible Lady Audley is for her actions. At times she refers to herself as mad, but seems to imply by this that she experiences unconventional desires and impulses. The idea that her mother was also mad, and that this madness was triggered by the experience of giving birth, seems to suggest that "madness" might actually be a reaction to the often stifling constraints of domestic life.
Heredity
In the Victorian period, heredity was an important concept because a broad range of character and personality traits were believed to be attributable to it. While the concept of genetics was not understood, the idea that mental illnesses could be passed down through generations was taken very seriously; so seriously, in fact, that it was sometimes assumed that the child of an insane or criminal person would invariably display those traits him- or herself. Lady Audley plays off of assumptions about heredity when, in order to start to create a case for Robert being insane, she tries to stir up suspicion about members of his family. The same theme is borne out when she explains that her own mother was mad and that she has therefore always assumed she will go mad as well. Heredity is an interesting theme because it could lessen Lady Audley's responsibility for her actions: she could be interpreted to have been doomed to villainous behavior through no fault of her own. On the other hand, especially because Dr. Mosgrave does not believe that she is mad, heredity can be seen as an ideology that Lady Audley manipulates to suit her own ends.
Marriage
Marriage is an important theme in virtually all sensation novels, and usually represented in a critical way. As Winifred Hughes writes, sensation fiction was "a pervasive mode of confronting and processing hidden fears, anxieties, and obsessions behind the dominant Victorian cultural institutions" (260), and marriage was one of the most dominant of those institutions. Lady Audley's Secret is no exception to this theme: many of the marriages it represents are unhappy. George and Helen Talboys do sincerely care for one another, but Helen is largely attracted to expectations of George's wealth and becomes frustrated when he cannot meet those expectations. The marriage between Lucy and Sir Michael is explicitly based on her attraction to his wealth and status. Phoebe only marries Luke because she is afraid of him hurting her if she rejects him. In all these cases, the women then go on to resent and deceive their spouses. In a time period when women only had limited legal rights and few opportunities to earn an independent income, Braddon seems to suggest that many marriages created out of these circumstances will be unsatisfying because they do not involve two equal partners. The two happy marriages that take place at the end of the novel, between Clara and Robert, and Alicia and Sir Harry, both involve women who have independent incomes and who are respected by their partners for having minds of their own.
