Original version, review 11/6/2005:
Once Fabienne Craigmont and Adam Ashworth were lovers: she a French aristrocrat just escaped from the Reign of Terror and he a rakish young idealist who belonged to a society of aristocrats who believed in free love and the rights of man--but not, you know, any interference in their own property. Now, twenty years later, Adam is a conservative country gentleman distressed over his daughter's troubled marriage and Fabienne is a stylish widow and famous patroness of the arts. Fabienne begins a correspondence with Mrs. Ravenwood, the author of tremendously popular Gothic novels, and goes in search of her, only to find a very uneasy and elusive Adam; she immediately concludes Mrs. Ravenwood is his mistress. Her error is obvious, but the author does have some actual surprises in store.
It's the depth of the characterization that makes this different from other Regencies: Fabienne and Adam's marriages aren't just convenient background details, but are given real shape and form and weren't unhappy. The two read like real adults who left each other and led real lives. Fabienne's correspondence with Mrs. Ravenwood and later conversations with Adam are explicit, witty, and wise; Mullany has given thought to what would make a young debutante do something so unlikely, instead of simply relying on the conventions of the genre. And Adam's attempts to deal with his daughter are awkward, imperfect, and sometimes absolutely wrong-headed: he isn't a fantasy father, and he messes up.
This isn't a perfect book; it should have ended about three-quarters of the way through, after which the machinations of separation become increasingly improbable and ridiculous. After a certain point, Fabienne collapses and seems to spend most of the rest of the book in uncharacteristic tears, a grave disappointment after the sense and strength she'd shown earlier; Adam takes over the book, giving me the sense that the author had his character worked out much more thoroughly than Fabienne's. So: far from perfect. But it's one of the most unusual romance debuts I've seen in a long time.
The expanded version does still drag on the separation too long, but it greatly improves the balance of attention between Adam and Fabienne. It feels like the story of both of them, rather than the story of Adam and also Fabienne.
ETA, 4/22/2013: Forgot to say: Now that I've read Mullany's Forbidden Shores
(as by Jane Lockwood), I'm disturbed that the only two gay/bisexual characters in her work are villains--and villains who attempt to punish the straight men they're in love with, often by using the women the straight guys love.