Hunter's Heart — Christina Hamlett

Just when Victoria Cameron's job as a legal assistant is getting dull, her boss assigns her to work for the firm's most prestigious client, the fabulously rich and devastatingly handsome Hunter O'Hare. Victoria is required to live in his home, a magnificent old castle he has transported, stone by stone, from Ireland to Virginia.
When Hunter confides that someone in his household is sending him death threats, Victoria agrees to help him uncover the would-be killer. But as her cool professionalism gives way to something much warmer, Victoria realizes that Hunter is hiding some dangerous secrets of his own.