Hastati Squad, the newest batch of freshman cadets at the UNSC's Corbulo Academy of Military Science, pays the price for cadet Thomas Lasky's tactics.
Thomas Lasky came to Corbulo Academy of Military Science with his mother and brother's impressive military careers hanging over his head. Haunted by ghosts from his past, he has serious doubts about the war he's expected to fight. As fellow cadet Chyler Silva tries to help him find his place at the academy, tensions with other squad members approach the breaking point.

Cadet Michael "Sully" Sullivan continues to decode the hidden ONI combat video as Lasky's struggle with his place in the UNSC ignites with fellow cadet Walter Vickers. After a classroom confrontation with Captain Mehaffey and a challenge from Chyler, Lasky pulls Hastati Squad back from the brink...at a terrible physical cost to himself.

Just as Hastati Squad is confronted by a video of secret ONI super-soldiers, their war and their whole universe are changed forever by a much more deadly surprise.

While Corbulo Academy is being destroyed by the Covenant invasion, the surviving cadets fight bravely alongside their only hope: The Master Chief.

After a terrifying night of combat and loss, Lasky makes a life-or-death decision to help the Master Chief... but will it be enough to save them all from the Covenant?