 Between the events of the first game and Halo 2 , the Chief and a few other survivors return to Earth , warning of an impending Covenant attack ; this attack forms the first mission of the game . Meanwhile , the Covenant , unaware of the destructive nature of the rings , attempt to fire another ring , Installation 05 , to fulfill their religious prophecy and to do so launch an attack on Earth . Helping the Chief to defend the Earth are Sergeant Avery Johnson and Commander Miranda Keyes . One race in the Covenant , the Elites , learn the truth about the rings and are led by a former Elite commander named the Arbiter ( also a player character ) to join forces with humanity to stop the firing of the ring . Though they are successful , the unexpected shutdown of the installation triggers a fail @-@ safe protocol , priming all the rings for firing from the Ark . 
