The Story - Part 1
The battle for the Earth.
In the wake of Halo's destruction, the Human-Covenant War has turned yet another dark corner.
While the Master Chief attempts to fend off the Covenant's invasion of Earth, an Elite Commander responsible for protecting Halo is being punished for his failure. But rather than receiving the customary sentence of death, he is elevated to Arbiter by the High Prophet of Truth. His first mission as the newly installed Arbiter is to silence a camp of heretics who preach that the activation of Halo will destroy all sentient life.
The Arbiter soon discovers that the heretics are operating under the influence of an Oracle, an ancient Forerunner AI construct which had been retrieved from Halo's debris field—343 Guilty Spark. Obeying the Prophets, the Arbiter destroys the enemy encampment, but he is left doubting his actions and wondering if there was any truth to the heretics' claims.