Archangel's Desire - Archangels' Series, #1

Raven Black is no martyr, but she has a secret she deems worth protecting. Placed into the care of Zadkiel, the Archangel of Mercy, Raven Black tries with all her might and main to hide her deadly secret. It's difficult to know who to trust or who to confide in, but Raven knows she's unwilling to be exploited to get the Archangels' greatest enemy. She seals her lips, refusing to speak and enduring the ensuing torture in silence.
After centuries of nothing but duty, Zadkiel is tormented by the hellhound Raven. The closer he gets to her, the more he discovers about this lethal beauty. With each passing moment an uncontrollable desire is awakened, and with it an ancient evil is provoked. When he discovers her secret, Zadkiel must choose between all of mankind and the woman he has come to love. Can he save her in time, or will his failure bring forth the end of days?