1810 England, the height of the Napoleonic wars. It was thought that humans walked the path of enlightenment leaving monsters and dark things behind. However, those monsters and night stalkers merely hide in the darkness, as a young maid, Bernadette, soon finds out.
And that's why she transforms when she feeds; well, that and scaring the crap out of her food, so she can feed on stronger emotions as well. I recall someone asking why some time ago. But... having sired a child vampire is 'frowned upon'? I wonder what she means by that. Well, I don't wonder, I know, but you might wonder.