Halo: Mortal Dictata: Book Three of the Kilo-Five Trilogy

"Welcome to humanity's new war: silent, high stakes, and unseen. This is a life-or-death mission for ONI's black-ops team, Kilo-Five, which is tasked with preventing the ruthless Elites, once the military leaders of the Covenant, from regrouping and threatening humankind again. What began as a routine dirty-tricks operation keeping the Elites busy with their own insurrection turns into a desperate bid to extract one member of Kilo-Five from the seething heart of an alien civil war"--