Sins of the Warrior - Grigori Legacy, #4

Heaven and Hell are at warHomicide detective Alexandra Jarvis's niece is missing and pregnant with Lucifer's child, her sister has descended into madness, and humanity has begun a relentless spiral toward self-destruction that Alex is desperate to stop. Now Michael, the Archangel she holds responsible for Earth's plight, has returned-and he's demanding her help to track a missing god. Heaven is losingFighting for the very survival of his own realm-and that of humanity-Michael's only chance to defeat Hell lies in returning Heaven's long-lost daughter to her throne before it's too late.
But first he'll have to convince Alex to help him-and keep her out of Hell's clutches long enough for her to do so. There can be no right choicesIn a desperate bid to save both their worlds, Alex and Michael must put aside their animosity and find a way to work together in the face of increasingly impossible decisions...and unimaginable sacrifice.