Dark Redemption — R. Peter Ubtrent

The F'gat Ynos have decimated planet after planet, leaving behind nothing but the dead. Ailanthus, Tethys, Xylella and Rohini now must bring what remains of the Noble Houses and humanity together, to begin the final battle that will decide whether humanity will survive or fall under the callous extermination of the Ynos. Cebrenia's plans to marry the emperor and bring her revenge against Nerodia are nearing completion, but her possession of a Thrumbo Worm will soon be discovered and her life will take a turn she had not expected. Nerodia and Mishi continue to move their rebellion forward, oblivious to the fact that there isn't much of humanity left to rule. Book five of the series begins the end of humanity's hegemony over the galaxy and brings to a crisis the very foundations of St. Aurum Gossomer and The Church of the Blessed Prophets, leaving disaster and chaos in its wake.