It’s the year 2552. Humanity has long been at war with the terrifying alien civilization that collectively calls itself The Covenant. This monstrous conglomerate of warlike species sees Humanity as a form of heresy against their religion. A religion based in the single-minded belief that a Great Journey awaits its faithful and that this Journey can be embarked upon by firing an array of vast, ring-like weapons scattered throughout the Galaxy.

These vast, terraformed rings are called Halos and have been long-abandoned by their mysterious and long-vanished creators, The Forerunners. This conflict, terrible and destructive though it is, has been complicated and compounded by a series of cascading events. One of these artificial worlds, these Halos, was discovered and subsequently destroyed by human forces, led by Spartan 117 – the Master Chief – the last fighting member of the legendary Spartan II military program and humanity’s last, best hope.