After crash-landing on the ring, Master Chief rallies surviving Marines and rescues Captain Keyes from a Covenant cruiser, the Truth and Reconciliation . They learn that the Covenant believe Halo is a religious "holy relic," but it is actually a super-weapon built by an ancient race called the .

The story of (2552 AD) follows a super-soldier and an AI fighting to save humanity from extinction on a mysterious alien ring-world . The Beginning: Arrival at Halo

After the human colony Reach is destroyed by the —an alliance of alien races—the human cruiser Pillar of Autumn makes a blind jump through slip-space. They emerge near a massive, artificial ring-shaped world known as Halo . As the ship is boarded by Covenant forces, Captain Keyes awakens the Master Chief (John-117), an augmented Spartan super-soldier, from cryosleep. The Chief is tasked with protecting Cortana , the ship's advanced AI, to prevent her data on Earth's location from falling into enemy hands. The Mission: Secrets of the Ring

: Master Chief and Cortana head to Halo's Control Room to activate the ring before the Covenant can. The Twist: The Flood Halo: Combat Evolved (Story Explained)