A Lady's Secret

Heroine: Petra d'Averio.
Hero: Robin, Earl of Huntersdown.
It opens in Jul 1764.

A novel in the Malloren World.
Follows, but is not connected to: A Most Unsuitable Man.
Followed by: The Secret Wedding.

A Lady's Secret was first published in Apr 2008 by Signet [9780451224194].
It reached #10 on the New York Times best seller list for Mass-Market Fiction.

More info on the book is available here: A Lady's Secret