Veiled Truth by Vivi Anna

Five years ago, virginal Lyra Magice had fled powerful dhampir Theron LeNoir's advances. But now an ancient text the dhampir possesses holds the key to solving murders that have plagued Necropolis. When another body is found and evidence points to the Mistress of the city, duty dictates that Lyra work with Theron—a man she regards as haughty, arrogant and immoral—to translate the symbols left at the crime scenes. But with their forced alliance comes darkly sensual dreams that leave her feeling wanton and achy...

Unwilling to reveal his dark past, the dhampir soon discovers that Lyra—a witch of great power—is to be the sacrificial virgin in a demonic scheme to open a portal to hell itself. Salvation will come only if Theron can win Lyra's trust—and her heart.