The Hidden Heart by Candace Camp

His life in ruins, Richard, Duke of Cleybourne, returns to his country estate to recover from a tragic loss he’d suffered four years earlier. However, his solitude is interrupted by the arrival of Miss Jessica Maitland, a flame-haired governess who presents her charge, Gabriella, as Richard’s new ward.
As if their unwelcome presence weren’t bad enough, Jessica also reveals that Gabriella’s life is in danger. Someone is after the young girl’s fortune—someone who might be closer than Richard could ever guess. And even with danger mounting, Richard finds it harder and harder to deny his growing feelings for Jessica.
When a raging snowstorm brings an odd assortment of guests to Cleybourne Castle, violence strikes, and Richard and Jessica find themselves on the hunt for a killer. Can they unravel the darkness at the heart of Cleybourne, before it’s too late?