John meets the monitor of the installation, 343 Guilty Spark, who recruits the Master Chief to fire the Halo and stop the Flood, but is stopped at the last moment by Cortana, turning Guilty Spark into the enemy.Ĭortana and John fight off Guilty Spark and the Halo's sentinels, and travel back to the wreckage of the Pillar of Autumn in an attempt to detonate the ship's reactor and destroy the ring. John tries to stop Keyes from releasing the Flood, but he is unsuccessful. Pillar of Autumn captain Jacob Keyes leads a team to recover weapons on the ring, only to find that the weapons are really a biological threat to all life known as the Flood. Spartan-II super-soldier John-117, along with his AI Cortana, discover that the ring is a super-weapon called Halo, and the Covenant want to use it against humanity. They are immediately intercepted by Covenant forces that force the Pillar of Autumn to crash-land onto the surface of the ring. The UNSC Pillar of Autumn, in an attempt to escape the aftermath of the Fall of Reach, makes a jump through slipspace, and ends up at a mysterious ring-shaped mega-structure orbiting a gas giant in the Soell system.
