Halo : First Strike - Eric S. Nylund

The Human-Covenant war rages on as the alien juggernaut sweeps inexorably toward its final goal: destruction of all human life.

Halo has been destroyed and the threat it posed to sentient life neutralized. But victory has come at a terrible cost for the UNSC. Thousands of valiant soldiers fell in the battle to prevent the alien construct from falling into the enemy's clutches. Now, everything depends on the Spartan known as the 'Master Chief'. Yet even with the aid of the artificial intelligence Cortana, the Master Chief will be hard-pressed to rescue survivors and evade the Covenant ships