In the House of the Wicked (Remy Chandler Series #5) by Thomas E. Sniegoski
Once he was known as the angel Remiel, but generations ago Boston PI Remy Chandler chose to renounce Heaven and live on Earth, where he found a secure place among us ordinary humans….
Though he may appear human, Remy has always been able to rely on Remiel—the embodiment of his angelic nature—whenever the situation calls for it. But now his human and angelic natures are sharing the same space, and Remy can feel himself becoming more and more volatile, no matter how hard he tries to control it.
Then Ashley Berg, a young woman who is like a daughter to him, vanishes without a trace. Dropping everything, Remy plunges into a frantic search for her, hoping all the while that her disappearance has nothing to do with him—or what he is.
But his hope is short-lived. A once-formidable sorcerer has taken her. The man wants vengeance against those he believes have wronged him—and Remy will be the instrument of his wrath…or Ashley will most certainly die.