Part of the Malloren series. Set in Georgian England.

BACK OF BOOK:

The Marquess of Ashart has been raised to be enemy to his cousin, the Marquess of Rothgar because the Dowager Lady Ashart believes the Mallorens were responsible for the untimely death of her youngest daughter, Rothgar's mother. However, at Christmas 1763, events conspire to bring Ash into his enemy's lair -- in other words, to join a Christmas house party at Rothgar Abbey. Some of the events concern an unwanted baby and a beautiful adventuress called Genova Smith. She can't be as innocent as she claims to be, especially as passion flames whenever they touch.