Along with staging this scene of revenge, Act III involves a case of mistaken identity—more precisely, the case of the woman behind the door. Indeed, one of the most ironic events in the act is that the villainness stands in the place of her foil, the consummately virtuous heroine. This confusion of women notwithstanding, however, it is here that the villainess will be definitively unmasked as a monster. Once trapped by Lord Goring, Cheveley dissolves into a "paroxysm of rage, with inarticulate sounds," her loss of speech giving way to an agony of terror that distorts her face. For a moment, a "mask has fallen," and Cheveley is "dreadful to look at." Her veneer of wit and beauty thus give way to a hidden beast.
Mrs. Cheveley's monstrosity is intimately related to what one might describe as her "bad" femininity, the femininity that belongs to the femme fatale. Whereas the play's "good woman"—a naive, candid, and earnest Lady Chiltern—embodies the virtues associated with womanliness, the witty and ambitious Mrs. Cheveley is characterized by what are conventionally considered feminine vices. Most notable is her duplicity. Throughout the play, Mrs. Cheveley appears as the product of "horrid combinations" that evoke her dangerous deceitfulness. In Act I, for example, Lady Basildon recoils from Mrs. Cheveley's "unnatural" union of daytime genius and nighttime beauty. Here the stage notes describe her as "lamia-like"—that is, part woman and part snake in her treacherous and deceptive nature. Lord Goring goes so far as to call her womanliness into question, remarking that for a fascinating woman such as her, sex is a challenge, not a defense. Mrs. Cheveley is aggressive and ambitious like a man; her sex is an obstacle to her desires. Horrid and unnatural, she is a monstrous woman.
Mrs. Cheveley's unmasking aside, the face-off between Goring and Cheveley also provides an opportunity to consider how the dandy might be associated with the notions of the feminine described here. Certainly the dandy is a figure of questionable masculinity, indeed often considered the paragon of the effeminate male. Lord Goring is no exception. In the previous section, we quoted Goring as declaring that "mothers are darlings," a remark that aligns him with women in familial life at least. His truer female double, however, is Mrs. Cheveley herself. Like Cheveley, Goring is artificial, amoral, cunning, duplicitous, irrational, and flamboyantly well dressed: all the traits associated with her dangerous and "unnatural" femininity. Goring is Mrs. Cheveley's only match because he can play her game of wiles. In light of Wilde's sodomy trials and interest in the homoerotic, one could speculate on how these motifs of unnatural and monstrous femininity that apply to the dandy might serve as ciphers for male effeminacy, gay or otherwise. As an additional observation in this vein, we might also note how Goring drops his "social face" in the encounter with his enemy. Strangely, at the end of the act, Goring, the consummate dandy-gentleman, will desperately threaten Cheveley with violence when she takes Lady Chiltern's letter. The usually cool Goring loses his sense of decorum, a loss that compromises his manliness even further.
Along with raising these gender issues, Act III also brings together the series of transactions that organize the play, transactions that involve three objects: Sir Robert's letter to Baron Arnheim, Mrs. Cheveley's diamond brooch, and Lady Chiltern's pink note to Lord Goring. In this scene, all pass through the hands of Mrs. Cheveley and Lord Goring at some point, once again emphasizing how the two are the play's most pivotal characters and positioning their face-off as the play's climax. As the "causes" of complication in the plot, it is fitting that all these objects emerge at the plot's most tense moment.
The central object of this encounter is of course the brooch/bracelet-turned-handcuff. As a symbol, it suggests numerous interpretations. A diamond snake, it is easily stands in for the evil woman, a skin-shedding villainness defined by duplicity and subterfuge. It is also a fitting weapon for our dandy-hero—that is, a luxury item that relies on guile rather than force and entraps its victim with style. This "wonderful"—or, in modern parlance, "fabulous"—ornament thus emblematizes the artistry and cunning of the dandy as much as it does the evil woman.