River of Fire: Fallen Angels #6:

A Desperate Lord... As rebel, soldier, hero, and spy, Kenneth Wilding had never known defeat. But nothing can save his heritage when he returns from the wars to an empty title and a ravaged estate. Nothing--until a stranger offers a devil's bargain: financial salvation in return for Kenneth's special subversive skills. Reluctantly Kenneth enters the household of the greatest artist in England to unmask a terrible crime. Instead, he discovers something infinitely more dangerous: a tantalizin...