In one year, Analise Saria Willoughby learns she is Fate; the angel Lucifer is her life mate; and, she is the only one who can bring a supernatural civil war to an end. Despite her reluctance to accept who she is and the powers she controls, Analise and Lucifer enjoy a year of mated bliss - until an injured shifter falls from the sky. To unravel the mysterious shifter's past, Analise must unlock the woman's memories. What she discovers is Fate's promise to a dead archangel - a promise that threatens to tear her and Lucifer's love apart even if it can save the life of his twin brother, Satan. If she is to keep Fate's promise, Analise must choose between her heart and her compassion. However, in the deadly war that promises the extinction of supernaturals and humans, there may not be room for both.