Having barely escaped the battle for Reach the crew of the Pillar of Autumn is forced to make a jump into Slipspace in hopes of evading the vast alien alliance hell-bent on wiping out humanity. But their destination brings them to an ancient mystery & an even greater struggle. In this far-flung corner of the universe floats a magnificently massive artificial ring world...a construct from a long lost race. The humans only hope of survival is to crash land on its surface & take the battle against the Covenant to the ground. But they soon discover that this enigmatic ring world is much more than it seems. Built 100 000 years ago by a civilization known as the Forerunners this Halo" is worshipped by the Covenant
- a sacred artefact that they hope will complete their religious quest for supposed transcendence. They will stop at nothing to control it. Engaged in a fierce ground battle Master Chief & Cortana go deep into the Halo Construct to uncover a dark secret; this enigmatic ring world is also the universes most dangerous weapon. Its purpose: the destruction of all sentient life. For the Forerunners built the HALO to battle the universes most vicious enemy
- a virtually unstoppable & suddenly reawakened force known as The Flood."