From the Darkness by Rebecca York

Breen Brennan and billionaire Troy London were once lovers. Now Troy has mysteriously disappeared, and Decorah Security sends Bree to Ravencrest, his isolated mansion on the Maine coast, to find out what happened. Posing as the tutor for Troy’s daughter, Dinah, Bree joins a household of suspicious characters, any one of whom could have killed Troy. Or is he being held against his will? And what about the unseen man who saves Bree from a fall to her death and then begins visiting her in the night, inflaming her passions with his hot kisses and knowing hands? Is he real or is he Troy’s ghost? Completely cut off from all help, Bree must figure out the mysteries of Ravencrest before powerful forces do away with her and Dinah. And is there any hope of finding Troy and rekindling the relationship they once had?