Halo 2 continues the story of Master Chief, the heroic super-soldier who defied the invading alien Covenant and survived. The Covenant leaders within Halo are angry at this unheard of event. To save face, they launch an invasion of our planet. Earth's defenses are breached, and we're all in danger -- unless Master Chief can lead a small military squad to victory against Covenant forces, in all-out guerilla warfare!