After their battle on the Forerunner planet Genesis, the Spartans of Blue Team and Fireteam Osiris are running for their lives from the AI Cortana.

Trouble seems to find Spartan Edward Buck no matter where he turns. A secret Office of Naval Intelligence mission could help, and has Buck reluctantly agreeing to reform his old team, Alpha-

Nine. But that includes the Spartan who Buck never wants to see again, the one who committed the ultimate betrayal...