One doesn't have to be human, to have humanity...

In 1832 England, to fall from the peerage is the kiss of death. Yet penniless Mordecai Dureance still has a life worth living: an honest vocation and a humble cottage where he, his new bride, Lynora, and his little brother, Isaac, can be a family. But Mordecai knows he's meant for more than gardening, if only society wouldn't shun the unholy byproducts of his horticultural experiments. When an ancient sect of vampires lures him into their hidden city, Nocturnus-an ornate labyrinth of tunnels deep beneath Tatabury's substratum-they promise wealth and acceptance beyond his imaginings. Discarding his human trappings, Mordecai embraces the darkness and its foundation of sins and blood. Yet he can't forget his light: the woman who loved him, poverty notwithstanding. To contact Lynora on topside is forbidden, but to live an eternity without her is unthinkable. So, Mordecai will break any laws-natural and unnatural alike-to bring her down into his monstrous world.

Lynora Dureance's life has crumbled under her blue-stockinged feet. Her wealthy family turned away when she married beneath their class. And now, mere weeks after abandoning Lynora and his young brother, her groom returns to claim her. When Lynora awakens, a victim of Mordecai's bite, she finds herself cloistered in a castle outside of Tatabury. Her rescuers, a clandestine group of women who raise bats, share her gruesome fate-not yet full vampire but starving for blood. By isolating themselves and holding galas to entrance men, the Sisterhood survives without resorting to murder. In contrast, the vampires' lethal feedings mark them as monsters. Each sister learns to defend herself, honing combative skills that will help Lynora reclaim her humanness and retrieve Isaac from the local orphan house. The one caveat: she must kill the seductive creature who tainted her blood-if she can see past his face and forget the brilliant gardener she once loved.

Lynora's and Mordecai's conflicting paths converge on one explosive night as they discover a strange blood-related illness infecting the children at the orphanage. Only by violating the laws that separate them, and bridging the broken trust between their worlds, can Lynora and Mordecai uncover the real monster and stop the evil force behind the plague-before it claims Isaac as its final victim.