Survivors from battle return to Reach. John confronts Dr. Halsey, and the lies of his past. The new prisoner seems to know John better than he knows himself. Determined to understand more, John turns back to the mystery artifact, which shows him something truly startling.

John and Makee come to terms with their shared vision. Halsey has one last chance to save her mission, and herself. As things come to a head, everyone must choose a side.

Beaten, battered, and betrayed, John 117 leads the Spartans on a suicide mission to find the Halo and save humanity. But at what price?