Lady Katherine Gainsworth is compromised into a marriage of convenience which takes her from her English home to the to Prussian Duchy of Heldenburg. Once there, she is introduced to her future in-laws, the van Krohnensteins, but finds they have some unconventional ideas of how to welcome her into the family. Although Heldenburg seems outwardly respectable, it has a thriving underworld of secret clubs devoted to illicit and bizarre pleasures. Katherine soon finds out from her ally and secret lover, Sergei, that the Count himself is no stranger to these places.Caught up in an intrigue of political treachery, jewel theft and sexual blackmail, Katherine is determined to keep control of her own destiny.