Halo 3 Plot

[JPetrillo]

Halo 3, like its predecessors, is set in the fictional Halo universe, taking place during the year 2553. According to the backstory, humans developed faster-than-light travel (using a Shaw-Fujikawa engine attached to a regular space shuttle) and colonized hundreds of planets before encountering the alien Covenant in 2525. The Covenant declares humanity an affront to their gods and began destroying human colonies by "glassing"—bombarding the planet with a barrage of plasma, turning its surface into glass. Despite efforts to keep the Covenant from finding Earth, a Covenant fleet discovers humanity's homeworld during Halo 2. By the beginning of Halo 3, the Covenant have arrived in full force on Earth, with most human resistance crushed.

The titular 'Halo' refers to massive ringworlds several hundred kilometers in diameter that are scattered across the galaxy. These rings were constructed thousands of years ago by an enigmatic race known as the Forerunners as a weapon of last resort against the parasitic alien species known as the Flood. When activated, the seven Halos would destroy all sentient life in the galaxy, thereby depriving the Flood of its food. The ringworlds were activated once in the distant past, and the Forerunners are believed to have perished. In Halo: Combat Evolved, a small human ship fleeing the Covenant stumbled upon one of these ringworlds, Installation 04. The humans manage to destroy the ring, stopping the Flood once again; the Covenant, unaware of the destructive nature of the rings, attempt to fire another ring during Halo 2 in order to fulfill their religious prophecy. One race in the Covenant, the Elites, learn the truth about the rings, and join forces with their onetime enemies, humanity, in order to stop the firing of the ring. Though they are successful, the unexpected shutdown of the installation triggers a failsafe protocol—all the rings are ready to fire from one single location, referred to as the Ark. Still oblivious to the true nature of the rings, the Covenant High Prophet of Truth and the remaining loyalist Covenant proceed to head to Earth, where they believe the Ark is buried.