When master chief wakes up after four years of hyper-sleep. He and the ingenious AI Cortona stumble across the supposedly extinct species known as the 'forerunners' and when the two partners find out what was said to be a great race of intelligent beings are really vengeful creatures that had once been human. A war had broken out long ago and for one millennia it raged on. But master chief is the only thing that stands between earth and those that have been after a weapon of mass destruction. The Composer, with the ability to turn humans into memetic creatures.