Cortana (level)

Cortana is the eighth campaign mission of Halo 3.

It takes place in a Flood infested High Charity and is involved with the Index from Installation 04.

Upon completing it on the Normal, Heroic, or Legendary difficulties, the player will earn the "The Key" achievement and 40 Gamerpoints.

A curious note to add to this level is that if you listen carefully, Cortana will say some quotes by Dr. Halsey from Halo: The Fall of Reach.