After decades of combat against the humans and then the traitorous Covenant Prophets, the Sangheili warrior Rtas ''Vadum—the Half-Jaw—has earned a long rest.

But not all of the Prophets perished in their holy city, High Charity, and now one of their fearsome Prelates has sworn his vengeance. This powerful threat has set a cataclysmic plan in motion—a plan to lure the Half-Jaw into a trap that will herald the utter destruction of the entire Sangheili race…