Annabelle Flynn is the sister of London's two biggest libertines, and her reaction has been to become the picture of purity. But the sensual nature of her family has not been lost on her and she is troubled by urges she dare not follow. She ignores the demands of her body and instead throws herself into two different activities. One is pursuing a proper marriage in Society and the other is trying to save her broken brother by following him into the shocking Donville Masquerade, part of a hell run by the mysterious Marcus Rivers. By day, Annabelle pursues ladylike endeavors and seeks a staid husband to combat the wild reputations of her brothers. By night, she inserts herself into Marcus's business... and eventually she finds herself seduced into his bed. But can a not-quite-proper lady and an entirely unsuitable cad find anything in common outside of the bedroom? And will Annabelle be willing to trade passion for cold, calculated 'perfection'?