Here, Heyer takes on the notions of what it is to be 'respectable' in terms of the Regency Period. The heroine helps run a gaming den, hence the title, Faro's Daughter (Faro is a kind of card game). She becomes emotionally entangled with a young aristocrat who has formed an attachment to her and wishes to marry her. Naturally his family don't approve. It is all very well for a young man to waste his money on cards and loose women, but it is not very well for him to then marry into such a world.
The hero, Max, is sent to rescue his addle pated relation from such a terrible fate, and naturally becomes entangled with the young femme fatale herself, with all kinds of disastrous consequences, which naturally in Heyer's world, all work themselves out neatly before the end of the book!
What I found difficult about this book was the fact that I couldn't really warm to the heroine, Deborah, too easily. It seemed she was more a vehicle than a character in her own right. She never really fleshed out well, as so many of Heyer's other characters do.
Despite this it was still a delightful read and one of the most productive ways I've found to spend a wet Saturday afternoon. You won't be disappointed.