Humanity is at war. For generations, humans traveled the stars and worked together to settle worlds under the banner of the United Nations Space Command. Now that peace has been shattered by insurrectionists—causing a galaxy-spanning civil war. Cadet Thomas Lasky and his fellow students at Corbulo military academy now train to make this war their future. But Lasky is conflicted about his path, and his resolve is tested when the academy comes under attack from a terrifying alien assault. Lasky and his fellow cadets fight for survival, only to find assistance from a mysterious ally—a mythic, armored supersoldier known as Master Chief.